Axle back exhaust

[JAG247]

Hey everybody, this is my first post here on the forums. I recently purchased a new Race Red 2025 Mustang GT with the 10 speed a few months ago. I’m really enjoying it so far. However, my GT came with the non-active exhaust system, so I’m looking for a bit more volume. I’d really rather not do a full cat back. I’m just looking for more noise so a simple Axle back system will be fine. I will probably never touch the mid either. I don’t want it too rowdy. I have narrowed it down between the Roush and Borla S-type axle backs. I really like the Roush because it has the quad tip and the non-active Borla does not. I’ve heard the Roush can get quite loud though. I’m looking for a nice aggressive note that’s definitely noticeable over stock but I don’t want it to be obnoxious. Is there anybody out there that has experience with these Axle backs? Would love to hear from y’all. Thanks.

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[Steve@Lethal]

Hey everybody, this is my first post here on the forums. I recently purchased a new Race Red 2025 Mustang GT with the 10 speed a few months ago. I’m really enjoying it so far. However, my GT came with the non-active exhaust system, so I’m looking for a bit more volume. I’d really rather not do a full cat back. I’m just looking for more noise so a simple Axle back system will be fine. I will probably never touch the mid either. I don’t want it too rowdy. I have narrowed it down between the Roush and Borla S-type axle backs. I really like the Roush because it has the quad tip and the non-active Borla does not. I’ve heard the Roush can get quite loud though. I’m looking for a nice aggressive note that’s definitely noticeable over stock but I don’t want it to be obnoxious. Is there anybody out there that has experience with these Axle backs? Would love to hear from y’all. Thanks.

You can get a quad non active Borla but it would be the 18-23 one. People have made it work too. But if you are looking to not change your headers, cats, or factory resonator, the Roush will be fine. It's more of a glass pack muffler while the Borla is an actual muffer.

With whatever you decide to do, please let me know if I can help!
https://www.lethalperformance.com/s...-2026-mustang-gt-dark-horse/exhaust/axlebacks

 

[JAG247]

You can get a quad non active Borla but it would be the 18-23 one. People have made it work too. But if you are looking to not change your headers, cats, or factory resonator, the Roush will be fine. It's more of a glass pack muffler while the Borla is an actual muffer.

With whatever you decide to do, please let me know if I can help!
https://www.lethalperformance.com/s...-2026-mustang-gt-dark-horse/exhaust/axlebacks

Hey, thanks for the reply. I read that the most recent design of the Roush Axle back is actually an open chambered muffler and not a “straight through” design like the Borla. With that being said, I’m leaning towards the BORLA. I want to minimize drone as well and I know BORLA is really good at doing that.

You mentioned that the 18-23 BORLA Axle back will work on the S650. Other than making the modification to the rear valance, what else do you have to do to make it fit?

 

[Will2]

I have a Roush axle-back for 15-17 Mustang GT's, single-tip on each side.
It fits S650 GT's, but the original Roush tips are little short for the S650 chassis, should extend out like 1" longer for my tastes. I had to buy separate tips, 12" length, and they stick out like 1" too long now. Ideal would be ~10.5-11", or have a muffler shop weld on some tips.

The sound is great. It is loud, and seems like it got a little louder than when first installed. I'd say it's now 75% as loud as a muffler delete (I ran that for a while before the Roush axle-back). Similar tone to a pure muffler delete: deep bassy rumble, no rasp. That's the sound I like, but most people tend to get X/H-pipes, which IMO all sound kinda raspy, and especially raspy if combined with a non-OEM muffler.

There isn't much drone, but I technically any resonant frequency could count as drone, and I can hear some ~1900RPM with the Roush axle-back, versus 1400-1600RPM on a muffler delete. The muffler delete was outright uncomfortable sometimes due to the volume level.

 

[Koverboy1911]

Hey, thanks for the reply. I read that the most recent design of the Roush Axle back is actually an open chambered muffler and not a “straight through” design like the Borla. With that being said, I’m leaning towards the BORLA. I want to minimize drone as well and I know BORLA is really good at doing that.

You mentioned that the 18-23 BORLA Axle back will work on the S650. Other than making the modification to the rear valance, what else do you have to do to make it fit?

Other than making the modification to the valance there's nothing else you have to do. I have a '24 GT and I made no other modifications other than going to quad tips with the valance.

 

[DeeDub SC]

Hey everybody, this is my first post here on the forums. I recently purchased a new Race Red 2025 Mustang GT with the 10 speed a few months ago. I’m really enjoying it so far. However, my GT came with the non-active exhaust system, so I’m looking for a bit more volume. I’d really rather not do a full cat back. I’m just looking for more noise so a simple Axle back system will be fine. I will probably never touch the mid either. I don’t want it too rowdy. I have narrowed it down between the Roush and Borla S-type axle backs. I really like the Roush because it has the quad tip and the non-active Borla does not. I’ve heard the Roush can get quite loud though. I’m looking for a nice aggressive note that’s definitely noticeable over stock but I don’t want it to be obnoxious. Is there anybody out there that has experience with these Axle backs? Would love to hear from y’all. Thanks.

I have 2024 GT with manual and standard exhaust and replaced the resonator with a Ford Performance x-pipe with excellent results to my ears. Really opened up the sound without getting too raspy. Was only about $400 with installation at a decent shop, so probably considerably cheaper than your options. Just a suggestion to consider.

 

[Steve@Lethal]

Hey, thanks for the reply. I read that the most recent design of the Roush Axle back is actually an open chambered muffler and not a “straight through” design like the Borla. With that being said, I’m leaning towards the BORLA. I want to minimize drone as well and I know BORLA is really good at doing that.

You mentioned that the 18-23 BORLA Axle back will work on the S650. Other than making the modification to the rear valance, what else do you have to do to make it fit?

Honestly just the quad rear valance is needed for it. I can't say it is 100% but I have seen many people do it.

 

[DarkMatterGrey]

I have an S550 Roush black dual tip axle back on my S650. It’s more of a straight through resonator style. Not overly loud except cold start up in my garage. Compared to other mustangs, including active exhaust vehicles like my son’s S500 without a resonator delete (x or h pipe) it’s relatively quiet. So you definitely won’t be the loudest mustang around. I bought it as new old stock (never installed) a couple years ago for under $500.

If you want quad tip, Roush makes them now, and you can get a template to cut the existing rear valence in case you don’t want to buy a new one.

 

[MustangMental]

RTR Quad Tip Exhaust Conversion Kit (24+ Mustang) - RTR Vehicles -- RTR just came out with these, or you can order a new quad tip valence or just Dremel it out. Lots of youtube videos on it. Quad tip or dual tip they won't make any difference in sound.

 

[JAG247]

RTR Quad Tip Exhaust Conversion Kit (24+ Mustang) - RTR Vehicles -- RTR just came out with these, or you can order a new quad tip valence or just Dremel it out. Lots of youtube videos on it. Quad tip or dual tip they won't make any difference in sound.

Hey, I really like the idea of those RTR pieces. However, those are crazy expensive for what they are. I watched a video on YouTube where a guy cut his with a razor knife. They came out, super clean and almost looked factory. I will probably take that route. That being said, I may not even cut it all. I may go ahead and buy the single tip version. Still on the fence on which system to go with though. I kinda like BORLA atak now but I’m afraid it might be too loud.

 

[MidwayJ]

I had a Roush axle back on the S550 I recently sold. It's one of the louder aftermarket mufflers, but it sounds great and isn't too loud or raspy as long as you keep the stock resonator in place. Cold starts are fairly loud but it quiets down when it warms up. It's pretty quiet when you're just cruising along but comes to life when you rev it.

 

[JAG247]

Anybody out there with the Borla Axle back? I understand that it is deeper than the factory, but I’m wondering how much louder it is?

 

[JAG247]

I have an S550 Roush black dual tip axle back on my S650. It’s more of a straight through resonator style. Not overly loud except cold start up in my garage. Compared to other mustangs, including active exhaust vehicles like my son’s S500 without a resonator delete (x or h pipe) it’s relatively quiet. So you definitely won’t be the loudest mustang around. I bought it as new old stock (never installed) a couple years ago for under $500.

If you want quad tip, Roush makes them now, and you can get a template to cut the existing rear valence in case you don’t want to buy a new one.

How’s the interior noise drone etc? I found a set for a S550 pretty cheap that’s in like new condition. How’s the fitment? Somebody else commented that the tips didn’t stick out far enough since it’s designed for the S550.

 

[DarkMatterGrey]

How’s the interior noise drone etc? I found a set for a S550 pretty cheap that’s in like new condition. How’s the fitment? Somebody else commented that the tips didn’t stick out far enough since it’s designed for the S550.

Interior noise isn’t that bad. They’re really not that loud. My son’s stock s550 with active exhaust is louder. I’ve been tempted to get an H pipe and feel there’s room in the volume of sound, except for cold starts in the garage. I live in a nice neighborhood and don’t want to draw the ire of my neighbors.

Fitment isn’t bad they stick out just fine for me. They seem to be stock length, but I could see someone wanting them longer, but not me. I like the fact I was able to get the black tip ones and with the way they fit, they look stealthy as my car is dark gray.

 

[JAG247]

Interior noise isn’t that bad. They’re really not that loud. My son’s stock s550 with active exhaust is louder. I’ve been tempted to get an H pipe and feel there’s room in the volume of sound, except for cold starts in the garage. I live in a nice neighborhood and don’t want to draw the ire of my neighbors.

Fitment isn’t bad they stick out just fine for me. They seem to be stock length, but I could see someone wanting them longer, but not me. I like the fact I was able to get the black tip ones and with the way they fit, they look stealthy as my car is dark gray.

Would you happen to have any other videos such as drive-bys, revving, etc?

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