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

[jmagnus87]

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
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.

Also, for a total of $32,000 and you have a great performing track car that will out-perform a good portion of competition AND still be reasonably street-able you sure got the bargain of the century. I bought mine using x-plan pricing and paid $38,900 for mine brand new. I'll say the performance package adds way more value than it costed back then!! I'm probably about $15,000 additional deep past my original buy in and I'm still on the super cheap side for what i have lol

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[Rodpwnz]

There is a noticeable difference when you do something like Steeda IRS Base kit but what a lot of people don't mention is that this also increase NVH mostly the harshness part on not ideal roads. But the tradeoff in harshness is also a gain in lap times the IRS Base kit for me made the car so much more predictable in transitions and not feeling the whole Diff and Cradle wight shifting to the outside in transition is making a huge difference in how planted the car is. So great mod for performance not so great for highway cruising.

I always hear about NVH, but usually nobody specifies what part of NVH they are experiencing. I absolutely do not want any new annoying noises or vibrations, but can totally deal with a slightly stiffer ride.

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!

I think I will do the BMR CB005(Or Kelltrac posi-lock) and the steeda subframe alignment kit. Maybe the Differential Bushings kit from BMR. Kelly's mods in that video seem too involved and much more risk of adding more complications and NVH(Noise) for me as a daily driver with only occasional track days. I would be having a shop install these and frankly am also a little concerned if they will be able to do it right.

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

What kind of NVH did the MMR camber plates add? I have a set that I am going to have a shop install with the rear IRS mods.

 

[jmagnus87]

@Rodpwnz the subframe alignment bushings were the number one thing that ends up cross-threading the body of your car which you cannot replace!! I wouldn't have a shop do this without the kelltrac stud kit!!! The same goes for the BMR alignment bushings or any other manufacturer for that matter. They remove ALL of the factory installation tolerance for assembly. There's a reason ford left big gaping holes between the cradle and the bolts.
the CB005 is a good kit, so is the steeda kit and don't increase NVH much if at all. Kelltracs design is cut specific to the bushings and sits in the bushings like a cap over it. IMO, that's the best but more difficult to install.
the differential insert bushings also are a huge upgrade with next to no NVH but also requires lowering the subframe, i can't say enough about the studs from kelltrac. I cross threaded the body of my car myself taking my time and being careful installing the diff bushings kit. If i had the studs literally every job would have been 400% easier and that's not an exaggeration!!
this isn't a quick easy bolt on for any of the manufacturers kits and can have severe consequences... so make sure whatever shop you bring it to cares about your car like you do. There are plenty of shops out there doing good work and take pride in their work, but sadly there's way more butchering cars and not even knowing they did it!!

 

[Howitzer]

I always hear about NVH, but usually nobody specifies what part of NVH they are experiencing. I absolutely do not want any new annoying noises or vibrations, but can totally deal with a slightly stiffer ride.



I think I will do the BMR CB005(Or Kelltrac posi-lock) and the steeda subframe alignment kit. Maybe the Differential Bushings kit from BMR. Kelly's mods in that video seem too involved and much more risk of adding more complications and NVH(Noise) for me as a daily driver with only occasional track days. I would be having a shop install these and frankly am also a little concerned if they will be able to do it right.




What kind of NVH did the MMR camber plates add? I have a set that I am going to have a shop install with the rear IRS mods.

The MMR camber plates added a bit of noise for me. When hitting bumps on the street it's very noticeable. This is due to the integrated solid top mount it has instead of re-using the stock rubber top mount. I don't really mind it, but...if this was a daily, I'd probably go for something that re-uses that rubber top mount.

 

[Howitzer]

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!

I got Apex 25mm spacers to use. And yes, extended studs. They are the ARP studs that came with the ford performance wheel hubs. These are 3" from the hub face (3.5" overall i believe).

These spacers have small notches on the bottom to help with getting them off if they get stuck. I wanted some that had that since I'd be changing often. OPMustang also makes some very similar. I just got the new setup within the past month so haven't had a chance to test it all, just tested fitment. The spacers shouldn't be a pain at all, they just slide on/off.

Spacers:

New Hubs w/ Extended Studs:

New Wheel Set for Track - SVE R350 19x11 wrapped in Kumho V730 305/30

 

[bnightstar]

@Rodpwnz the subframe alignment bushings were the number one thing that ends up cross-threading the body of your car which you cannot replace!!

Can you expand on that are you talking about steeda bushings inserts that are around the 12 bolts that goes through the subframe ? I can't see how that could be an issue if done properly.

 

[Ballistica]

I got Apex 25mm spacers to use. And yes, extended studs. They are the ARP studs that came with the ford performance wheel hubs. These are 3" from the hub face (3.5" overall i believe).

These spacers have small notches on the bottom to help with getting them off if they get stuck. I wanted some that had that since I'd be changing often. OPMustang also makes some very similar. I just got the new setup within the past month so haven't had a chance to test it all, just tested fitment. The spacers shouldn't be a pain at all, they just slide on/off.

Spacers:

New Hubs w/ Extended Studs:

New Wheel Set for Track - SVE R350 19x11 wrapped in Kumho V730 305/30

Great, thank you! And just to confirm, you're running the extended studs on both set's of wheels, correct? Not switching them out when you swap the spacers?

Those SVE wheels look great!

 

[Howitzer]

Great, thank you! And just to confirm, you're running the extended studs on both set's of wheels, correct? Not switching them out when you swap the spacers?

Those SVE wheels look great!

Thanks! Yes, the studs stay. Just have to use open lugs. Both my wheel sets use the smaller diameter lugs, so it works out nicely, same lugs for both sets. I'm using monster open ended lugs.

A dirty pic of what these look like on the 19x10 set without spacer:

 

[bnightstar]

You didn't add a rear differential cooler? You don't get rear differential overheating warnings? I read about people overheating all the time. The FPRS 2015 GTs have a wicked trunk mounted cooling set up. I wish I had taken a photo of it when I was there.

The FPRS 2015 GT cars were run all day every day at Texas heat. Really different than what normal track day enthusiasts do to there cars when driving them on track.

 

[jmagnus87]

Can you expand on that are you talking about steeda bushings inserts that are around the 12 bolts that goes through the subframe ? I can't see how that could be an issue if done properly.

The installation tolerance is the void around those 4 blue bolts into the body. The bushings take up almost all of that installation tolerance, not a problem if you know with 100% accuracy that you're perfectly aligned to the subframe. If this is what you mean by "done properly" you're correct, but
1) the average shop doesn't have the time to pay that much attention to it, as they're in business to make money and most good technicians make money on flat rate hours
2) mine required a ratchet strap from the front corner of subframe to the frame of the car cranked pretty tight after the first 3 we're LOOSELY INSTALLED just 2 threads to get the thing to line up "properly" to the car.
3) kelltrac confirmed this in an email to me when i talked to him about the stud kit and he said he's seen that it's mostly the drivers side front one that always seems to be cross-threaded. So maybe you start with that bolt in first and do the other three and you're good? I don't know i haven't taken that bolt back out after i bought the tap and re-tapped it.
4) kelltracs stud kit comes with the tap for this very reason. But at least with the studs, you can lower the cradle completely, put the 4 studs in, then the 4 alignment bushings, then your cradle lockout kit, then align the cradle with the 4 studs (should be super easy because they're extra long for this purpose and sticks out of the car, with the bolts you're guessing where hole center is) and set the nuts on and crank each corner evenly until it's fully seated and voila you're on your way!

 

[bnightstar]

The installation tolerance is the void around those 4 blue bolts into the body. The bushings take up almost all of that installation tolerance, not a problem if you know with 100% accuracy that you're perfectly aligned to the subframe. If this is what you mean by "done properly" you're correct, but

That's why the instructions say work on 1 side only.

When we did it on my car we dropped the credle on the driver side first put the bushings and the bolts then did the same at the passanger side and then got everything tide at the same time. No issue what so ever. But I can see how a non specialised shop could mess that up so I get the risks. I was wondering if you are referring to a post install risk ? BTW Mustang GT4 for example is running very similar solution for rear bushings.

 

[jmagnus87]

That's why the instructions say work on 1 side only.

When we did it on my car we dropped the credle on the driver side first put the bushings and the bolts then did the same at the passanger side and then got everything tide at the same time. No issue what so ever. But I can see how a non specialised shop could mess that up so I get the risks. I was wondering if you are referring to a post install risk ? BTW Mustang GT4 for example is running very similar solution for rear bushings.

IIRC, the instructions were referring to front and rear because if you kept one side up there was no way you were getting that front diff bushing in IMO. Which is what i did, i did rear first then front. Got the passenger side front back in went to put in the drivers side and felt it chewing up my frame all the way. Shop was closing for the day wasn't my shop i had to gtfo or else family buddy would have been rippin.
post install may have the same issue and likely part of why that front drivers side is the common one. I don't work on others cars everyday just going by what me and kelltrac talked about. You can only re-thread that thing so many times before the metal is gone

Edit, i should mention i was doing the diff bushings lockouts at the same time. Not just the subframe alignment bushings. Made sense to do both at the same time to me because you're already in there. That may be the key difference here

 

[Rodpwnz]

The MMR camber plates added a bit of noise for me. When hitting bumps on the street it's very noticeable. This is due to the integrated solid top mount it has instead of re-using the stock rubber top mount. I don't really mind it, but...if this was a daily, I'd probably go for something that re-uses that rubber top mount.

BTW, I just realized I have MM Camber plates, NOT MMR. Not sure if that makes a difference, these are what I have, but not installed yet: https://www.americanmuscle.com/mm-caster-camber-plates-2015.html

 

[Renatus]

Hiii. i have a 2015 pp1. The interior and exterior is a dynamite. I would like to add more power to the engine. What do you suggest? What modifications i made so far is ford track performance suspension kit, outlaw exhaust and an airfilter which come with an Ngauge.

 

[HKusp]

Hiii. i have a 2015 pp1. The interior and exterior is a dynamite. I would like to add more power to the engine. What do you suggest? What modifications i made so far is ford track performance suspension kit, outlaw exhaust and an airfilter which come with an Ngauge.

Are you looking for naturally aspirated (N/A) power gains or going the forced induction (turbo/supercharger)? Either way, in the tech section there are sub forums for NA and forced induction. You will find all the information you need/want there.

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