Howitzer's Long Term Street to Track 2015 Mustang GT Build

[Howitzer]

So...here we are. Nearly 8 years since I've had this car, I guess now is a good a time as any to finally make a build thread.

2015 Mustang GT Base
Street/Track - more track than street these days

Modifications
Suspension:
BMR SP083 handling springs
FRPP track shocks/struts,
MMR Camber plates
Steeda front lateral control arms
Steeda IRS braces
Steeda IRS alignment dowels
BMR rear adjustable toe links
BMR rear vertical links
lower k brace (PP1 car part)
strut tower and cowl brace (PP1 car part)
AED rear control arms

Powertrain:
2021 ported intake manifold with IMRC lockouts
18+ injen air intake with restrictor cutout for 120mm MAF
JLT oil separator (driver and passenger side)
Texas Speed longtube headers with GESI G-Sport UHO cats
MBRP Street catback w/ H pipe - full 3" from headers
MGW shifter w/ flatstick handle
Exedy Mach 500 clutch
3.55 Torsen differential and driveshaft from 2021 donor car
Whiteline diff bushing inserts KDT-934 w/ upgraded BMR hardware
Dyno tuned by Luis Ortiz
Auto-Blip module (for mostly rev-match downshifts)
GT500 Valve Covers
Performance Pack radiator

Brakes/Wheels+
Front Brembo brakes from PP car
Vorshlag air deflectors
PP Belly pan with brake ducts
Brake Pads - Carbotech XP12 front / XP10 Rear (track)
Ford Racing Performance front Hubs w/ ARP Extended Studs
Monster Open Lugs - Black Chrome
MRR M350 Wheels 19x10 square (street - 285/35/19)
LMR SVE 350R wheels 19x11 ET50 square (track - 305/30/19)
25mm APEX front slip on spacers (track)

Interior:
Android 10.2" radio
Premium dash trim and light-up door sills
JBL 609C Speakers
Revesol Flat Bottom Steering Wheel - Matte Carbon, leather, silver stitch

Exterior:
Cutout OEM upper grill with black diamond mesh
OEM lower grill from premium car with black diamond mesh behind openings
AFE air scoop behind grill to intake
Trackspec Side Vents
MMD Rear Spoiler - Matte black
PP front lip spoiler


How it started (2015)

How it's going (as of 2022):

A little history...
The year is 2015 and I was in process of getting rid of all my motorcycles (I had 4 of them - track, street, dirt, and another track bike I had been working on) due to a bad street accident about a year prior...getting T-boned by a truck is not fun and I'm probably lucky to be alive. This was not a first street accident, and I figured I may not be around to see what the outcome of a 3rd incident would be. I had ridden for about 8 years prior to any accidents...that last year of riding was just not my year.

I had never been very interested in mustangs...but the S550 was intriguing to me since they finally had an independent rear suspension. I was ready to get back in a RWD vehicle and I wanted something decently fast to kind of make up for getting rid of my bikes.
I found a great deal at a local dealer - they only had 1 used 2015 mustang GT and it was this triple yellow base model. They also had a 2014 GT track pack. Test drove them both...and chose the 2015. I knew mustangs had a vast aftermarket so anything I wanted changed, I figured I could do it myself.
Purchased it lightly used for a little over 26k with 4k miles on it. It was traded cuz the guy that had it before realized he didn't want a manual transmission. Score for me.

After driving it for nearly a year, I realized the suspension and tires were...inadequate we'll say. I still find it comical they equipped these with 235 width all season tires. Could never get traction when I needed it, and behavior was unpredictable - really a combination I don't want. So the first things I did was get a set of 19x10 MRR M350 wheels from this very forum, BMR handling springs and ford racing track shocks/struts. Man...those changes alone made a HUGE difference.

Several years into owning the car...it started to become more frustrating to drive than not and was a love/hate relationship for a little while...I kept thinking about getting something different. I just found myself not being able to drive the car the way I really wanted. Out on public roads, there's just no way to really push the car in any sane manner...It's hard to realize and explain but I experienced the difference when I first started tracking motorcycles.

So...I started thinking about getting back into track days but with a car...almost still got rid of the car in favor of a Fiesta ST to keep running costs down a bit and to get a car that could be more manageable...but...I'm glad I've kept the mustang. It's a great, reliable platform to work with. It still puts a smile on my face every time I do get to really drive it. I started tracking the car end of 2021...aaaand...I've went mod crazy the past year and a half to really make the car perform its best and to behave the way I want. I'll probably make a few posts here to highlight some of these changes.

Sponsored

 

[plresultsman]

So...here we are. Nearly 8 years since I've had this car, I guess now is a good a time as any to finally make a build thread.

2015 Mustang GT Base
Street/Track - more track than street these days

Modifications
Suspension:
BMR SP083 handling springs
FRPP track shocks/struts,
MMR Camber plates
Steeda front lateral control arms
Steeda IRS braces
Steeda IRS alignment dowels
BMR rear adjustable toe links
BMR rear vertical links
lower k brace (PP1 car part)
strut tower and cowl brace (PP1 car part)

Powertrain:
2021 ported intake manifold with IMRC lockouts
18+ injen air intake with restrictor cutout for 120mm MAF
JLT oil separator
Texas Speed longtube headers with GESI G-Sport UHO cats
MBRP Street catback w/ H pipe - full 3" from headers
MGW shifter w/ flatstick handle
Exedy Mach 500 clutch
3.55 Torsen differential and driveshaft from 2021 donor car
Whiteline diff bushing inserts KDT-933 w/ upgraded BMR hardware
Dyno tuned by Luis Ortiz

Brakes/Wheels+
Front Brembo brakes from PP car
Vorshlag air deflectors
PP Belly pan with brake ducts
Brake Pads - Carbotech XP12 front / XP10 Rear (track)
Ford Racing Performance front Hubs w/ ARP Extended Studs
Monster Open Lugs - Black Chrome
MRR M350 Wheels 19x10 square (street)
LMR SVE 350R wheels 19x11 square (track)

Interior:
Android 10.2" radio
Premium dash trim and light-up door sills
JBL 609C Speakers
Revesol Flat Bottom Steering Wheel - Matte Carbon, leather, silver stitch

Exterior:
Cutout OEM upper grill with black diamond mesh
OEM lower grill from premium car with black diamond mesh behind openings
Trackspec Side Vents
MMD Rear Spoiler - Matte black
PP front lip spoiler


How it started (2015)

How it's going (as of 2022):

A little history...
The year is 2015 and I was in process of getting rid of all my motorcycles (I had 4 of them - track, street, dirt, and another track bike I had been working on) due to a bad street accident about a year prior...getting T-boned by a truck is not fun and I'm probably lucky to be alive. This was not a first street accident, and I figured I may not be around to see what the outcome of a 3rd incident would be. I had ridden for about 8 years prior to any accidents...that last year of riding was just not my year.

I had never been very interested in mustangs...but the S550 was intriguing to me since they finally had an independent rear suspension. I was ready to get back in a RWD vehicle and I wanted something decently fast to kind of make up for getting rid of my bikes.
I found a great deal at a local dealer - they only had 1 used 2015 mustang GT and it was this triple yellow base model. They also had a 2014 GT track pack. Test drove them both...and chose the 2015. I knew mustangs had a vast aftermarket so anything I wanted changed, I figured I could do it myself.
Purchased it lightly used for a little over 26k with 4k miles on it. It was traded cuz the guy that had it before realized he didn't want a manual transmission. Score for me.

After driving it for nearly a year, I realized the suspension and tires were...inadequate we'll say. I still find it comical they equipped these with 235 width all season tires. Could never get traction when I needed it, and behavior was unpredictable - really a combination I don't want. So the first things I did was get a set of 19x10 MRR M350 wheels from this very forum, BMR handling springs and ford racing track shocks/struts. Man...those changes alone made a HUGE difference.

Several years into owning the car...it started to become more frustrating to drive than not and was a love/hate relationship for a little while...I kept thinking about getting something different. I just found myself not being able to drive the car the way I really wanted. Out on public roads, there's just no way to really push the car in any sane manner...It's hard to realize and explain but I experienced the difference when I first started tracking motorcycles.

So...I started thinking about getting back into track days but with a car...almost still got rid of the car in favor of a Fiesta ST to keep running costs down a bit and to get a car that could be more manageable...but...I'm glad I've kept the mustang. It's a great, reliable platform to work with. It still puts a smile on my face every time I do get to really drive it. I started tracking the car end of 2021...aaaand...I've went mod crazy the past year and a half to really make the car perform its best and to behave the way I want. I'll probably make a few posts here to highlight some of these changes.

If I may ask, much money and time invested to get it to this point?

 

[Howitzer]

If I may ask, much money and time invested to get it to this point?

Oof...going to ask to quantify all that huh? Cost...probably somewhere around $6k, not including consumables or wheel sets. I was able to get a few things second hand. Only labor I've paid for is to install the headers. Everything else was done in my garage on jack stands.
Time...who knows. It's been enjoyable working on it though and I never rushed myself to finish a job since I have another car for "daily" runs. Biggest job was the diff swap and had to fix a cracked bushing so that took some extra time.

 

[Rodpwnz]

So...here we are. Nearly 8 years since I've had this car, I guess now is a good a time as any to finally make a build thread.

2015 Mustang GT Base
Street/Track - more track than street these days

Modifications
Suspension:
BMR SP083 handling springs
FRPP track shocks/struts,
MMR Camber plates
Steeda front lateral control arms
Steeda IRS braces
Steeda IRS alignment dowels
BMR rear adjustable toe links
BMR rear vertical links
lower k brace (PP1 car part)
strut tower and cowl brace (PP1 car part)

Powertrain:
2021 ported intake manifold with IMRC lockouts
18+ injen air intake with restrictor cutout for 120mm MAF
JLT oil separator
Texas Speed longtube headers with GESI G-Sport UHO cats
MBRP Street catback w/ H pipe - full 3" from headers
MGW shifter w/ flatstick handle
Exedy Mach 500 clutch
3.55 Torsen differential and driveshaft from 2021 donor car
Whiteline diff bushing inserts KDT-933 w/ upgraded BMR hardware
Dyno tuned by Luis Ortiz

Brakes/Wheels+
Front Brembo brakes from PP car
Vorshlag air deflectors
PP Belly pan with brake ducts
Brake Pads - Carbotech XP12 front / XP10 Rear (track)
Ford Racing Performance front Hubs w/ ARP Extended Studs
Monster Open Lugs - Black Chrome
MRR M350 Wheels 19x10 square (street)
LMR SVE 350R wheels 19x11 square (track)

Interior:
Android 10.2" radio
Premium dash trim and light-up door sills
JBL 609C Speakers
Revesol Flat Bottom Steering Wheel - Matte Carbon, leather, silver stitch

Exterior:
Cutout OEM upper grill with black diamond mesh
OEM lower grill from premium car with black diamond mesh behind openings
Trackspec Side Vents
MMD Rear Spoiler - Matte black
PP front lip spoiler


After driving it for nearly a year, I realized the suspension and tires were...inadequate we'll say. I still find it comical they equipped these with 235 width all season tires. Could never get traction when I needed it, and behavior was unpredictable - really a combination I don't want. So the first things I did was get a set of 19x10 MRR M350 wheels from this very forum, BMR handling springs and ford racing track shocks/struts. Man...those changes alone made a HUGE difference.

So...I started thinking about getting back into track days but with a car...almost still got rid of the car in favor of a Fiesta ST to keep running costs down a bit and to get a car that could be more manageable...but...I'm glad I've kept the mustang. It's a great, reliable platform to work with. It still puts a smile on my face every time I do get to really drive it. I started tracking the car end of 2021...aaaand...I've went mod crazy the past year and a half to really make the car perform its best and to behave the way I want. I'll probably make a few posts here to highlight some of these changes.

Thanks for sharing your experience and build thus far - It's funny that you post this now because I was about to DM you to ask about IRS mods! I think everything you've done is in good taste and with good reason behind it. And at only $6K total, I consider it pretty good value and performance.

What would you recommend for someone who wants best bang for buck, with no added NVH on a 95% street car and 5% road course? (285x4 300TW tires, OEM magneride, MMR camber plates).

It's amazing how we can go into these cars thinking it will be a street car that is trackable, and somehow they become track cars that are streetable! I find myself going to the track 1-2x a quarter maybe, but thinking about the car, track and mods very often!

 

[Howitzer]

Thanks for sharing your experience and build thus far - It's funny that you post this now because I was about to DM you to ask about IRS mods! I think everything you've done is in good taste and with good reason behind it. And at only $6K total, I consider it pretty good value and performance.

What would you recommend for someone who wants best bang for buck, with no added NVH on a 95% street car and 5% road course? (285x4 300TW tires, OEM magneride, MMR camber plates).

It's amazing how we can go into these cars thinking it will be a street car that is trackable, and somehow they become track cars that are streetable! I find myself going to the track 1-2x a quarter maybe, but thinking about the car, track and mods very often!

lol...thanks! And yeah, very true...tracking the car wasn't even on my mind originally, but here we are. Definitely still think about what I can (or SHOULD) do.

As for your car...a PP1 car with magneride is already a great start. If I was only doing 5% track, I'd probably be good with that setup alone (well, for a little while anyway). That being said, I'm not overly familiar with magneride, but I know Ford Performance makes a decent kit if you're looking at tightening up the overall handling further: https://performanceparts.ford.com/part/M-9602-M. No idea what the specs on the sway bars in that kit are though, I'm sure someone around here has done that before.

To help with getting power down in corners - essentially the steeda stop the hop kit is a good package (first 3 things mentioned are in that package):

• The Steeda IRS braces are good, as are the rear vertical links (I have BMR - steeda also makes some nice ones) - I recommend getting some with polyurethane bushings to not add any NVH.
• IRS alignment dowels are nice if you're planning additional work back there - it helps to make sure the rear is (and stays) aligned if you're loosening or dropping the subframe. Can be a PITA to do if your rear subframe is not already perfectly aligned.
• If you do upgrade the front sway bar, you may want to upgrade the sway bar end links as the stock ones are prone to bend with stiffer bars. I'm actually still on my stock sways, so have not bothered to upgrade the end links yet - I have been keeping an eye on them for any bending.
• And before any of that, I'd highly suggest doing some rear diff puck inserts and either a bolt through setup for the diff or adding the metal sleeve and upgraded hardware that BMR and Lethal Performance make. This is so you can hopefully avoid cracking those soft rear diff bushings and/or shearing diff bolts. Tracking it and putting more power down in corners will definitely wear that out faster. I use whiteline KDT-934 for the pucks - softest ones I could find and no NVH. Steeda has some softer ones as well, but I don't believe they are as soft.
  • Link to the cracked bushing issue: https://www.mustang6g.com/forums/threads/differential-bushing-finally-failed.130993/
  • Hardware upgrade kit: https://www.bmrsuspension.com/?page=products&productid=1764

Even with all the changes to my car, the only thing that's added noticeable NVH, are the MMR camber plates.

 

[Crew4991]

So...here we are. Nearly 8 years since I've had this car, I guess now is a good a time as any to finally make a build thread.

2015 Mustang GT Base
Street/Track - more track than street these days

Modifications
Suspension:
BMR SP083 handling springs
FRPP track shocks/struts,
MMR Camber plates
Steeda front lateral control arms
Steeda IRS braces
Steeda IRS alignment dowels
BMR rear adjustable toe links
BMR rear vertical links
lower k brace (PP1 car part)
strut tower and cowl brace (PP1 car part)

Powertrain:
2021 ported intake manifold with IMRC lockouts
18+ injen air intake with restrictor cutout for 120mm MAF
JLT oil separator
Texas Speed longtube headers with GESI G-Sport UHO cats
MBRP Street catback w/ H pipe - full 3" from headers
MGW shifter w/ flatstick handle
Exedy Mach 500 clutch
3.55 Torsen differential and driveshaft from 2021 donor car
Whiteline diff bushing inserts KDT-934 w/ upgraded BMR hardware
Dyno tuned by Luis Ortiz
Auto-Blip module

Brakes/Wheels+
Front Brembo brakes from PP car
Vorshlag air deflectors
PP Belly pan with brake ducts
Brake Pads - Carbotech XP12 front / XP10 Rear (track)
Ford Racing Performance front Hubs w/ ARP Extended Studs
Monster Open Lugs - Black Chrome
MRR M350 Wheels 19x10 square (street - 285/35/19)
LMR SVE 350R wheels 19x11 square (track - 305/30/19)
25mm front slip on spacers (track)

Interior:
Android 10.2" radio
Premium dash trim and light-up door sills
JBL 609C Speakers
Revesol Flat Bottom Steering Wheel - Matte Carbon, leather, silver stitch

Exterior:
Cutout OEM upper grill with black diamond mesh
OEM lower grill from premium car with black diamond mesh behind openings
Trackspec Side Vents
MMD Rear Spoiler - Matte black
PP front lip spoiler


How it started (2015)

How it's going (as of 2022):

A little history...
The year is 2015 and I was in process of getting rid of all my motorcycles (I had 4 of them - track, street, dirt, and another track bike I had been working on) due to a bad street accident about a year prior...getting T-boned by a truck is not fun and I'm probably lucky to be alive. This was not a first street accident, and I figured I may not be around to see what the outcome of a 3rd incident would be. I had ridden for about 8 years prior to any accidents...that last year of riding was just not my year.

I had never been very interested in mustangs...but the S550 was intriguing to me since they finally had an independent rear suspension. I was ready to get back in a RWD vehicle and I wanted something decently fast to kind of make up for getting rid of my bikes.
I found a great deal at a local dealer - they only had 1 used 2015 mustang GT and it was this triple yellow base model. They also had a 2014 GT track pack. Test drove them both...and chose the 2015. I knew mustangs had a vast aftermarket so anything I wanted changed, I figured I could do it myself.
Purchased it lightly used for a little over 26k with 4k miles on it. It was traded cuz the guy that had it before realized he didn't want a manual transmission. Score for me.

After driving it for nearly a year, I realized the suspension and tires were...inadequate we'll say. I still find it comical they equipped these with 235 width all season tires. Could never get traction when I needed it, and behavior was unpredictable - really a combination I don't want. So the first things I did was get a set of 19x10 MRR M350 wheels from this very forum, BMR handling springs and ford racing track shocks/struts. Man...those changes alone made a HUGE difference.

Several years into owning the car...it started to become more frustrating to drive than not and was a love/hate relationship for a little while...I kept thinking about getting something different. I just found myself not being able to drive the car the way I really wanted. Out on public roads, there's just no way to really push the car in any sane manner...It's hard to realize and explain but I experienced the difference when I first started tracking motorcycles.

So...I started thinking about getting back into track days but with a car...almost still got rid of the car in favor of a Fiesta ST to keep running costs down a bit and to get a car that could be more manageable...but...I'm glad I've kept the mustang. It's a great, reliable platform to work with. It still puts a smile on my face every time I do get to really drive it. I started tracking the car end of 2021...aaaand...I've went mod crazy the past year and a half to really make the car perform its best and to behave the way I want. I'll probably make a few posts here to highlight some of these changes.

Congrats on a beautiful build! I love that Triple Yellow color.

 

[Ewheels]

Following!

That's funny, we have a very similar story in regards to motorcycles. I rode for 7 years and also stopped after my second accident for the same exact reason...might not survive the 3rd. Rather than getting T-boned, I flipped on the highway and the bike landed on me.

Glad to see more track enthusiasts make build threads!

 

[Rodpwnz]

lol...thanks! And yeah, very true...tracking the car wasn't even on my mind originally, but here we are. Definitely still think about what I can (or SHOULD) do.

As for your car...a PP1 car with magneride is already a great start. If I was only doing 5% track, I'd probably be good with that setup alone (well, for a little while anyway). That being said, I'm not overly familiar with magneride, but I know Ford Performance makes a decent kit if you're looking at tightening up the overall handling further: https://performanceparts.ford.com/part/M-9602-M. No idea what the specs on the sway bars in that kit are though, I'm sure someone around here has done that before.

To help with getting power down in corners - essentially the steeda stop the hop kit is a good package (first 3 things mentioned are in that package):

• The Steeda IRS braces are good, as are the rear vertical links (I have BMR - steeda also makes some nice ones) - I recommend getting some with polyurethane bushings to not add any NVH.
• IRS alignment dowels are nice if you're planning additional work back there - it helps to make sure the rear is (and stays) aligned if you're loosening or dropping the subframe. Can be a PITA to do if your rear subframe is not already perfectly aligned.
• If you do upgrade the front sway bar, you may want to upgrade the sway bar end links as the stock ones are prone to bend with stiffer bars. I'm actually still on my stock sways, so have not bothered to upgrade the end links yet - I have been keeping an eye on them for any bending.
• And before any of that, I'd highly suggest doing some rear diff puck inserts and either a bolt through setup for the diff or adding the metal sleeve and upgraded hardware that BMR and Lethal Performance make. This is so you can hopefully avoid cracking those soft rear diff bushings and/or shearing diff bolts. Tracking it and putting more power down in corners will definitely wear that out faster. I use whiteline KDT-934 for the pucks - softest ones I could find and no NVH. Steeda has some softer ones as well, but I don't believe they are as soft.
  • Link to the cracked bushing issue: https://www.mustang6g.com/forums/threads/differential-bushing-finally-failed.130993/
  • Hardware upgrade kit: https://www.bmrsuspension.com/?page=products&productid=1764

Even with all the changes to my car, the only thing that's added noticeable NVH, are the MMR camber plates.

I agree with you that the car is good as is, but also would love to just tighten the IRS down a bit more since everyone has been raving about it. I just am having a hard time fully understanding how our IRS works, each of our bushings, our toe links, our bearings, the bushing materials, etc.

The end result of all my research would also be to understand why is each company(Steeda, BMR, Kelltrac) kits look so different, and which ones will cause the least NVH and/or be the most effective and/or best value?

Also, I'm not sure if my bushings are actually gone - I'm thinking it could be U-joint related issue since I hear a singular "clunk" when engaging to D or Reverse, or sometimes random singular "clunk" when accel or decel. Apparently there are 2x U joints in the drivetrain?

My head is spinning trying to get a handle on all this... usually mod shopping is supposed to be fun!

 

[chuckhammer]

So...here we are. Nearly 8 years since I've had this car, I guess now is a good a time as any to finally make a build thread.

2015 Mustang GT Base
Street/Track - more track than street these days

Modifications
Suspension:
BMR SP083 handling springs
FRPP track shocks/struts,
MMR Camber plates
Steeda front lateral control arms
Steeda IRS braces
Steeda IRS alignment dowels
BMR rear adjustable toe links
BMR rear vertical links
lower k brace (PP1 car part)
strut tower and cowl brace (PP1 car part)

Powertrain:
2021 ported intake manifold with IMRC lockouts
18+ injen air intake with restrictor cutout for 120mm MAF
JLT oil separator
Texas Speed longtube headers with GESI G-Sport UHO cats
MBRP Street catback w/ H pipe - full 3" from headers
MGW shifter w/ flatstick handle
Exedy Mach 500 clutch
3.55 Torsen differential and driveshaft from 2021 donor car
Whiteline diff bushing inserts KDT-934 w/ upgraded BMR hardware
Dyno tuned by Luis Ortiz
Auto-Blip module

Brakes/Wheels+
Front Brembo brakes from PP car
Vorshlag air deflectors
PP Belly pan with brake ducts
Brake Pads - Carbotech XP12 front / XP10 Rear (track)
Ford Racing Performance front Hubs w/ ARP Extended Studs
Monster Open Lugs - Black Chrome
MRR M350 Wheels 19x10 square (street - 285/35/19)
LMR SVE 350R wheels 19x11 square (track - 305/30/19)
25mm front slip on spacers (track)

Interior:
Android 10.2" radio
Premium dash trim and light-up door sills
JBL 609C Speakers
Revesol Flat Bottom Steering Wheel - Matte Carbon, leather, silver stitch

Exterior:
Cutout OEM upper grill with black diamond mesh
OEM lower grill from premium car with black diamond mesh behind openings
Trackspec Side Vents
MMD Rear Spoiler - Matte black
PP front lip spoiler


How it started (2015)

How it's going (as of 2022):

A little history...
The year is 2015 and I was in process of getting rid of all my motorcycles (I had 4 of them - track, street, dirt, and another track bike I had been working on) due to a bad street accident about a year prior...getting T-boned by a truck is not fun and I'm probably lucky to be alive. This was not a first street accident, and I figured I may not be around to see what the outcome of a 3rd incident would be. I had ridden for about 8 years prior to any accidents...that last year of riding was just not my year.

I had never been very interested in mustangs...but the S550 was intriguing to me since they finally had an independent rear suspension. I was ready to get back in a RWD vehicle and I wanted something decently fast to kind of make up for getting rid of my bikes.
I found a great deal at a local dealer - they only had 1 used 2015 mustang GT and it was this triple yellow base model. They also had a 2014 GT track pack. Test drove them both...and chose the 2015. I knew mustangs had a vast aftermarket so anything I wanted changed, I figured I could do it myself.
Purchased it lightly used for a little over 26k with 4k miles on it. It was traded cuz the guy that had it before realized he didn't want a manual transmission. Score for me.

After driving it for nearly a year, I realized the suspension and tires were...inadequate we'll say. I still find it comical they equipped these with 235 width all season tires. Could never get traction when I needed it, and behavior was unpredictable - really a combination I don't want. So the first things I did was get a set of 19x10 MRR M350 wheels from this very forum, BMR handling springs and ford racing track shocks/struts. Man...those changes alone made a HUGE difference.

Several years into owning the car...it started to become more frustrating to drive than not and was a love/hate relationship for a little while...I kept thinking about getting something different. I just found myself not being able to drive the car the way I really wanted. Out on public roads, there's just no way to really push the car in any sane manner...It's hard to realize and explain but I experienced the difference when I first started tracking motorcycles.

So...I started thinking about getting back into track days but with a car...almost still got rid of the car in favor of a Fiesta ST to keep running costs down a bit and to get a car that could be more manageable...but...I'm glad I've kept the mustang. It's a great, reliable platform to work with. It still puts a smile on my face every time I do get to really drive it. I started tracking the car end of 2021...aaaand...I've went mod crazy the past year and a half to really make the car perform its best and to behave the way I want. I'll probably make a few posts here to highlight some of these changes.

Cool build. I thought our cars would overheat the differential oil without a cooler being installed? I don't see one in your build list and you've been going at it for a while now. Maybe that problem is overstated.

 

[Ewheels]

Cool build. I thought our cars would overheat the differential oil without a cooler being installed? I don't see one in your build list and you've been going at it for a while now. Maybe that problem is overstated.

Better/thicker oil and heat wrap around the exhaust pipes near the diff seem to be the easiest fix. Mine never go above 250°F

Unless you've added a decent amount of power (ie. more heat) and are endurance racing, it's not a very common mod anymore.

 

[Howitzer]

Cool build. I thought our cars would overheat the differential oil without a cooler being installed? I don't see one in your build list and you've been going at it for a while now. Maybe that problem is overstated.

As EWheels stated - heavier oil helps (as does exhaust wrapping). I swapped over to (BG Ultraguard) 75-140w oil in my old diff when I started tracking the car. I just swapped over to a torsen diff and put the same kind of 75-140w oil in. Will be testing that out soon.

I probably should keep better track of the diff temps since I don't even have a temp sensor connection being a 2015 (and originally non-pp car). The new diff does have a temp sensor in it, so maybe I could wire some kind of gauge.

 

[chuckhammer]

Happy to hear that.

 

[Ballistica]

So...here we are. Nearly 8 years since I've had this car, I guess now is a good a time as any to finally make a build thread.

2015 Mustang GT Base
Street/Track - more track than street these days

Modifications
Suspension:
BMR SP083 handling springs
FRPP track shocks/struts,
MMR Camber plates
Steeda front lateral control arms
Steeda IRS braces
Steeda IRS alignment dowels
BMR rear adjustable toe links
BMR rear vertical links
lower k brace (PP1 car part)
strut tower and cowl brace (PP1 car part)

Powertrain:
2021 ported intake manifold with IMRC lockouts
18+ injen air intake with restrictor cutout for 120mm MAF
JLT oil separator
Texas Speed longtube headers with GESI G-Sport UHO cats
MBRP Street catback w/ H pipe - full 3" from headers
MGW shifter w/ flatstick handle
Exedy Mach 500 clutch
3.55 Torsen differential and driveshaft from 2021 donor car
Whiteline diff bushing inserts KDT-934 w/ upgraded BMR hardware
Dyno tuned by Luis Ortiz
Auto-Blip module

Brakes/Wheels+
Front Brembo brakes from PP car
Vorshlag air deflectors
PP Belly pan with brake ducts
Brake Pads - Carbotech XP12 front / XP10 Rear (track)
Ford Racing Performance front Hubs w/ ARP Extended Studs
Monster Open Lugs - Black Chrome
MRR M350 Wheels 19x10 square (street - 285/35/19)
LMR SVE 350R wheels 19x11 square (track - 305/30/19)
25mm front slip on spacers (track)

Interior:
Android 10.2" radio
Premium dash trim and light-up door sills
JBL 609C Speakers
Revesol Flat Bottom Steering Wheel - Matte Carbon, leather, silver stitch

Exterior:
Cutout OEM upper grill with black diamond mesh
OEM lower grill from premium car with black diamond mesh behind openings
Trackspec Side Vents
MMD Rear Spoiler - Matte black
PP front lip spoiler


How it started (2015)

How it's going (as of 2022):

A little history...
The year is 2015 and I was in process of getting rid of all my motorcycles (I had 4 of them - track, street, dirt, and another track bike I had been working on) due to a bad street accident about a year prior...getting T-boned by a truck is not fun and I'm probably lucky to be alive. This was not a first street accident, and I figured I may not be around to see what the outcome of a 3rd incident would be. I had ridden for about 8 years prior to any accidents...that last year of riding was just not my year.

I had never been very interested in mustangs...but the S550 was intriguing to me since they finally had an independent rear suspension. I was ready to get back in a RWD vehicle and I wanted something decently fast to kind of make up for getting rid of my bikes.
I found a great deal at a local dealer - they only had 1 used 2015 mustang GT and it was this triple yellow base model. They also had a 2014 GT track pack. Test drove them both...and chose the 2015. I knew mustangs had a vast aftermarket so anything I wanted changed, I figured I could do it myself.
Purchased it lightly used for a little over 26k with 4k miles on it. It was traded cuz the guy that had it before realized he didn't want a manual transmission. Score for me.

After driving it for nearly a year, I realized the suspension and tires were...inadequate we'll say. I still find it comical they equipped these with 235 width all season tires. Could never get traction when I needed it, and behavior was unpredictable - really a combination I don't want. So the first things I did was get a set of 19x10 MRR M350 wheels from this very forum, BMR handling springs and ford racing track shocks/struts. Man...those changes alone made a HUGE difference.

Several years into owning the car...it started to become more frustrating to drive than not and was a love/hate relationship for a little while...I kept thinking about getting something different. I just found myself not being able to drive the car the way I really wanted. Out on public roads, there's just no way to really push the car in any sane manner...It's hard to realize and explain but I experienced the difference when I first started tracking motorcycles.

So...I started thinking about getting back into track days but with a car...almost still got rid of the car in favor of a Fiesta ST to keep running costs down a bit and to get a car that could be more manageable...but...I'm glad I've kept the mustang. It's a great, reliable platform to work with. It still puts a smile on my face every time I do get to really drive it. I started tracking the car end of 2021...aaaand...I've went mod crazy the past year and a half to really make the car perform its best and to behave the way I want. I'll probably make a few posts here to highlight some of these changes.

Curious to know what spacers you’re using for your track setup and if you’re using extended wheel studs or not. Is it a pain to also switch out the spacers when you go back to the street setup? It’s an interesting setup!

 

[jmagnus87]

I agree with you that the car is good as is, but also would love to just tighten the IRS down a bit more since everyone has been raving about it. I just am having a hard time fully understanding how our IRS works, each of our bushings, our toe links, our bearings, the bushing materials, etc.

The end result of all my research would also be to understand why is each company(Steeda, BMR, Kelltrac) kits look so different, and which ones will cause the least NVH and/or be the most effective and/or best value?

Also, I'm not sure if my bushings are actually gone - I'm thinking it could be U-joint related issue since I hear a singular "clunk" when engaging to D or Reverse, or sometimes random singular "clunk" when accel or decel. Apparently there are 2x U joints in the drivetrain?

My head is spinning trying to get a handle on all this... usually mod shopping is supposed to be fun!

I was genuinely going to give up on Mustangs completely (I've had five different models since i was 18 and loved them all) until someone on this forum linked me this video:

I had been fighting with wheel hop since i bought my car in 2015 as well @Howitzer it was a very close battle between the yellow and competition orange for me, the dealership had both that day i got mine. I ended up with orange.
@chuckhammer, I've tracked my car many many times without any added horsepower or cooling for diff oil AND i have the Torsen gear driven diff, no issues whatsoever. I'm sure I'll start having issues after the supercharger though lol
All this being said, OP, I'm glad you're still here with us and giving the mustang a good name at the track for us! Getting the IRS to actually travel properly IMHO is the absolute best thing you can do to an S550 Mustang. Do everything you can to replace the components kelltrac mentions in the video. Nothing else for the car will be a better upgrade than this imo. Rock on ppl!

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