Catless exhaust setup solutions?

[Free Spirit]

I have a 2017 mustang GT and it has 2m 3in cat deletes with shitty welds, mounted up with some even shittier welds to an adapter then to am xpipe. And then 2.5in (including the xpipe) to the back where it looks like it has sr muffler delete. It's loud and I love loud. BUT. It sounds like dogshit. I don't want to deal with having new headers is installed to replace the cats so what are my options for making the car sound GREAT. A few ideas I've had was swap.to an hpipe (would I need a retune? I'm tuned on 93 by AED) and either a awe axle back or a valvetronic universal muffler set and mounting them just before the axle so I don't have to make custom hangers. Or hpipe leave the muffler delete and get some kinda of vibrant resonstor or another brand to try to remove the rasp and deepen the tone or some form of a jpipe. I'm a broke kid who lost all my money gambling on stupid shit so I can't afford more than maybe 500-800$ (parts only) I'm a welder with access to a welding shop so I can do all my own welding and fabrication. Made the mistake of paying someone for some welding on my old car and got shitty welds and spent 650$ on something that should've cost 50-100$. I'll be doing all my own work this time (Tig welding) please offer me some input. Clips for example of the car currently, just got it back after 3 months of repairs
Idle
75% ish throttle.
Light throttle/fun

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[robvas]

You don't need a retune for any exhaust changes

Put cats and mufflers back on it if you want it to sound normal instead of loud as crap and crappy sounding. Heck stick a an aftermarket middle resonator (Borla or magnaflow) back on it and that will quiet it right down

 

[Free Spirit]

You don't need a retune for any exhaust changes

Put cats and mufflers back on it if you want it to sound normal instead of loud as crap and crappy sounding. Heck stick a an aftermarket middle resonator (Borla or magnaflow) back on it and that will quiet it right down

As I mentioned, would like to stay catless. Because it's not worth 3k+ to buy new OEM headers and whatnot. What are my best options for keeping it loud. I like it loud it's just personal preference. But how to make it sound better without quieting it down to much.


Edit these coyotes aren't even very loud. WOT with a straightpipe is still quieter than a Harley at Idle.

 

[robvas]

As I mentioned, would like to stay catless. Because it's not worth 3k+ to buy new OEM headers and whatnot. What are my best options for keeping it loud. I like it loud it's just personal preference. But how to make it sound better without quieting it down to much.


Edit these coyotes aren't even very loud. WOT with a straightpipe is still quieter than a Harley at Idle.

You can put cats on without doing OEM headers...buy aftermarket ones and weld them in. If you're not boosted you don't have a good reason to be catless. It just stinks and makes it raspier.

Put the mufflers back on it at least. And actual mufflers, not Flowmaster Outlaws or Borla Ataks.

Loud is generally going to not sound as good.

The Coyote almost never sounds great, partially because of the how long the piping is and how far back the mufflers are. Listen to how much better a Coyote swap into a 1994-2004 Mustang sounds, because the muffler is the middle of the exhaust piping and not at the end.

 

[Free Spirit]

You can put cats on without doing OEM headers...buy aftermarket ones and weld them in. If you're not boosted you don't have a good reason to be catless. It just stinks and makes it raspier.

Put the mufflers back on it at least. And actual mufflers, not Flowmaster Outlaws or Borla Ataks.

Loud is generally going to not sound as good.

The Coyote almost never sounds great, partially because of the how long the piping is and how far back the mufflers are. Listen to how much better a Coyote swap into a 1994-2004 Mustang sounds, because the muffler is the middle of the exhaust piping and not at the end.

Well if I get the valvetronic universal muffler and mount them just after the midpipe wouldn't that help? But again I have 0 interest or desire to spend money on cats. I had plans to boost it before I lost roughly 35k with bad decisions. If I ever recover I'll still end up boosting it. But at the very least km thinking hpipe and do I do valved mufflers in the middle or or a jpipe/ resonator. I hear a lot about vibrant cutting the rasp and drone. (I currently have little drone unless I'm doing sub 45 mph in 6th gear.

 

[GregO]

500-800 bucks isn’t much in 2025.
Loud is cool until it totally ruins cabin conversations and wacks out hands free cell calls or just drones to an ear bleed and ear ringing while sleeping.
OP wants to GTAW a homemade system so have at it.
Get the dual mid muffler from Jones (search the Supercharger forum for part number).
You need rear resonance suppression so if skipping rear mufflers Weld up a set of Helmholtz chambers (take a look at Thermal R&D S550 cat back setup)
Or take that 800 bucks and buy the Thermal R&D system.

Oh Snap, it’s on sale and falls into your budget and it’s 304 !
https://thermalrd.com/products/2015-2017-ford-mustang-5-0l-gt-fastback-3-catback-exhaust

 

[Free Spirit]

These threads are so entertaining. I find it almost impossible to not engage at some level.
500-800 bucks isn’t much in 2025 so question #1 is material choices. Series 304 is off the table so stick to series 409.
Loud is cool until it totally ruins cabin conversations and wacks out hands free cell calls or just drones to an ear bleed and ear ringing while sleeping.
OP wants to GTAW a homemade system so have at it.
Get the dual mid muffler from Jones (search the Supercharger forum for part number).
You need rear resonance suppression so if skipping rear mufflers Weld up a set of Helmholtz chambers (take a look at Thermal R&D S550 cat back setup)
Or take that 800 bucks and buy the Thermal R&D system.
Oh Snap, it’s on sale and falls into your budget and it’s 304 !
https://thermalrd.com/products/2015-2017-ford-mustang-5-0l-gt-fastback-3-catback-exhaust

I've heard good and bad about thermal on this forum so I'd rather not touch them. But atm I found a steeda hpipe 304 for 100$. And an awe touring axle back also stainless, for 260 + 50 shipping so 310+ whatever tax will be. That's maybe 480$ for an axle back and midpipe. Should I also toss in some resonators between the midpipe and axle back? Or some other way to deepen the tone? I'm sure I'll find better deals the more I look.

Edit, the thermal catback is only $790 brand new. Btw. But its 3in. I've heard there's no point touching 3in unless pushing 650+ whp. Which I am not

 

[GregO]

I've heard good and bad about thermal on this forum so I'd rather not touch them. But atm I found a steeda hpipe 304 for 100$. And an awe touring axle back also stainless, for 260 + 50 shipping so 310+ whatever tax will be. That's maybe 480$ for an axle back and midpipe. Should I also toss in some resonators between the midpipe and axle back? Or some other way to deepen the tone? I'm sure I'll find better deals the more I look.

You heard good and bad so now it’s a hard pass ?
Sorry man, I can’t help you any more than I have.

 

[Free Spirit]

You heard good and bad so now it’s a hard pass ?
Sorry man, I can’t help you anymore than I have.

Check my edit. But I've done my research on the company and my findings are that theres more bad than good with them and several instances of chargebacks being needed after they failed to deliver exhausts. It's not something I want to deal with so yes. Hard pass. I also don't like the way they sound and why would I buy an exhaust i don't like the sound of. Which by itself is a hard pass. Just my opinion though. Have a great day and thanks for the input.

 

[GregO]

Check my edit. But I've done my research on the company and my findings are that theres more bad than good with them and several instances of chargebacks being needed after they failed to deliver exhausts. It's not something I want to deal with so yes. Hard pass. I also don't like the way they sound and why would I buy an exhaust i don't like the sound of. Which by itself is a hard pass. Just my opinion though. Have a great day and thanks for the input.

As I suggested until I seen the Thermal on sale in your price range.
Jones mid muffler and Helmholtz rear whether that’s AWE, CORSA, Borla or a home made Helmholtz.

 

[Free Spirit]

As I suggested until I seen the Thermal on sale in your price range.
Jones mid muffler and Helmholtz rear whether that’s AWE, CORSA, Borla or a home made Helmholtz.

Is helmholtz a style of muffler or a brand?. I have been eyeing up the aee touring but I can't find any videos of it driving with a catless setup

Actually maybe my hearing is just bad I swear every video I find where they get in the throttle sounds identical to a straightpipe be it thermal, awe, borla, mbrp. Is this just how the coyote is? Is it even worth changing my exhaust setup if every time I go WOT it sounds like a trumpety straightpipe anyway? I'm lost at what do do here.

 

[GregO]

Is helmholtz a style of muffler or a brand?. I have been eyeing up the aee touring but I can't find any videos of it driving with a catless setup

Actually maybe my hearing is just bad I swear every video I find where they get in the throttle sounds identical to a straightpipe be it thermal, awe, borla, mbrp. Is this just how the coyote is? Is it even worth changing my exhaust setup if every time I go WOT it sounds like a trumpety straightpipe anyway? I'm lost at what do do here.

This is an Ark Grip Mustang exhaust with rear Helmholtz chambers. Those cancel out drone. AWE and CORSA mufflers have an internal Helmholtz whereas Ark, Thermal and even some MBRP use an external Helmholtz.

Catless is going to be a challenge to get the sound you desire. You’ll be way ahead if you start with the jones mid resonator/muffler. There are other mid options but the Supercharged guys have this jones mid combo dialed in both sound suppression and longevity.
Rear mufflers are a crapshoot. AWE’s sound good to me as does CORSA.
As far as 2.5” vs. 3” just get what is available within your budget don’t sweat the size difference.

 

[Wolfys11]

To make it sound better from a straight pipe like you have, you need to add resonators and mufflers. Of youre fine with just better sounding, stick on 2 vibrant ultraquiets on each side by the rear bumper, it will take out alot of the nasty sounds but keep a decent volume. If you want it to sound even better than that, add a straight thru resonated x or h pipe based off preference for deep or high pitch

800$ even for parts for a full catback isnt alot… any decent muffler or resonator is 200-300$ each, its hard to give you a god sounding coyote for no real budget, and anything 800$ isnt going to make it sound the best it can

 

[Free Spirit]

This is an Ark Grip Mustang exhaust with rear Helmholtz chambers. Those cancel out drone. AWE and CORSA mufflers have an internal Helmholtz whereas Ark, Thermal and even some MBRP use an external Helmholtz.

Catless is going to be a challenge to get the sound you desire. You’ll be way ahead if you start with the jones mid resonator/muffler. There are other mid options but the Supercharged guys have this jones mid combo dialed in both sound suppression and longevity.
Rear mufflers are a crapshoot. AWE’s sound good to me as does CORSA.
As far as 2.5” vs. 3” just get what is available within your budget don’t sweat the size difference.

Ignore my previous comments, given the sounds all sound the same (at least when catless) the thermal is the cheapest option so am I better off with that as a full catback or do I go for a awe axle back, h pipe setup with maybe the Jones resonators? Or toss the Jones resonators in with the thermal system? The awe I found for cheap is pretty heavily damaged but I can replace the clamp on tip easily the big dent would have to stay and I'm not sure it would fuction the same, 310 shipped vs 750 new.

 

[GregO]

@Free Spirit
The AWE has reflective sound chambers internally so with the damage I’d be cautious. If any internal welds are compromised there’s a good chance the mufflers will rattle.
The Jones has a built in crossover so the H-pipe or X-pipe is unnecessary.

About the Thermal R&D, I’ve never heard complaints, it’s mid pipe is a mix chamber not an H or X configuration. You could always add rear mufflers behind the Helmholtz like the Ark Grip system to lower the dB’s if needed.

TBH, if you have welding skills and access to a lift I’d jump on the Thermal R&D and refine it if needed. Plus you mentioned Supercharging and this system is sized appropriately.

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