Roush Axle-Back Exhaust Stainless Steel Mustang GT 2015-2017/ 2024

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Roush Stainless Steel Axle-Back Exhaust for all 2015, 2016, 2017 and 2024 GT Mustangs.

The Roush stainless steel axle-back exhaust (P/N: 421834) is designed to fit all 2015-2017 and 2024 GT Mustangs and will offer every owner the opportunity to install one of the most popular systems in the market today!

Roush’s stainless steel axle-back exhaust is the segment of your exhaust system that sits behind the rear axle, which is how it gets its name. It can even give you that classic muscle car roar that you’ve always wanted for your high-performance Mustang. This axle-back exhaust from Roush will offer your 2015-2017 or 2024 Mustang GT a distinct and aggressive sound. The highly tuned system will avoid the annoying drone or rasp that can occur with other competitive exhaust systems on the market. Needless to say, you will love the unmistakable sound and efficiency of your quality, new exhaust.

Backed By Popular Opinion and High-Quality Results

Constructed from 304 Stainless Steel, this axle back exhaust system features an exclusive open-chambered design that will not deteriorate over time, unlike conventional fiberglass packing material. The round exhaust tips are also made from stainless steel and finished with a unique process that provides heat resistance to color change. Like all Roush products, installation is quick, easy, and uses all factory hanger locations. The only necessary modification to the vehicle is that the factory exhaust will need to be cut off so that the new Roush axle-back can easily install with the provided clamps.

When you buy this axle-back exhaust, you get more than just a dependable exhaust system.

Features and Benefits:
- Fills OEM Ford Rear Valance
- Zero Impact on Emission Devices
- Straight-Thru Design Yields Higher Airflow and Performance 
- Full 304 Stainless Steel Construction
- Includes Clamps and Installation Instructions

*Installation requires cutting of the factory exhaust piping. Once the modifications have been made to the factory exhaust system, Installation is a simple bolt-in procedure.

How well do you want your Mustang to look and perform? With any of the parts from Roush Performance, you can give it a major performance overhaul, and add some visual styling that will make your Mustang stand apart from the crowd. CJ Pony Parts is a Roush Top 10 Dealer and offers parts from Roush Performance for many different years of Mustang, many of which are in stock and ready to ship today.

Manufacturer Part Number: 421834

If you want a great exhaust that will improve the performance of your ride and give you that signature muscle car roar, then this Roush axle-back exhaust is for you. Plus, we offer all of our products at some of the lowest prices on the market so you can get the products you need in no time. Best of all, when you order before 5 PM EST, we can get your purchase on the road that same day, and we can almost always do it for free! Get the Roush Stainless Steel Axle-Back Exhaust for your 2015-2017 or 2024 Mustang GT from CJ Pony Parts today!

California Residents: Proposition 65 Warning

Installation Difficulty


Novice skill is required for this installation.

Installation Videos

Video Transcript

The Roush axle back was one of the more popular systems for the 2011 through 2014 Coyotes, especially if you keep the rest of your exhaust system stock. It offered a very aggressive tone when on the throttle, but at highway speeds it was very tame and offered no drone at all. When Roush announced a similar system for the 2015 Mustang, we knew we had to get our hands on one, so today we're going to show you how to install one on your 2015 Mustang, and we'll provide you some sound clips.

Unlike the previous models, any axle back on the 2015 Mustang will require cutting, which actually isn't that big of a deal. The system comes with everything you need for installation, including the two mufflers, which are full stainless steel along with these two chrome four-inch tips. Before we get started with the installation, we're going to play you some sound clips of a factory 2015 GT exhaust.

For this installation, a lift or a jack and jack stands, half-inch ratchet or low torque electric half-inch impact gun, 15 millimeter socket, Sawzall, file, marker, and safety glasses. Like I said, with any axle back system, you're going to have to cut. Previous models would have clamps in this neighborhood, but in the case of the 15's, everything is welded. But cutting really is no big deal.

The instructions from Roush are very clear on where to cut, so you want to mark it over here. I'll explain where you're actually going to mark it and then you can cut it. The instructions provided by Roush tell you to cut the pipe closest to the tangent of the curve. If you're like me, you probably read more car magazines than paid attention in geometry class. I'll explain what the tangent is. What that is, is the closest straight line to the curve of the pipe. You want to follow the curve over and as soon as it gets to a straight section, that's roughly where you're going to cut. Do the same thing on both sides. To make sure you're in the right neighborhood, grab the Roush muffler. You're going to hold it up approximately where it's going to go. Then make sure this lines up with where you're going to cut.

Everything looks good, so we can cut the pipe. Since you'll need two hands to control the saw, if you don't have someone to hold the pipes for you, stuff some rags up in here. That way, it doesn't bounce up against your balance. Now we can slide the muffler off the factory hanger. Then you'll want to de-burr it before we put the new pipe on. First, slide the clamp over our muffler, make sure it's a spot where you can reach in to tighten it. I'm going to put it up into the hanger and slide it over the factory pipe. Now grab the supply tips that are fully adjustable in this case. Slide a clamp on, and make sure you get it where you want it. You can push it all the way down and bottom it out, but usually I like it a little bit better and pull it out a little bit. Go back and tighten everything down.

Roush recommends against using an air impact for this part of the job. Use a hand tool or, like I said, I have a low torque impact gun, which is electric which will work fine. I'm going to repeat the process on the other side. All right, it fits great. Let's see how it sounds. It sounds killer. It's the same aggressive sound we got from the older Roush system. Sounds just as good on the 15.

Inside the car, the tone is very similar to the 11 through 14. It has that same kind of aggressive sound to it, but it's quieter. I actually don't think the exhaust is quieter. It's just that the 15 is actually much quieter inside so I think it's deadening a lot of the sound out. When you're at highway speeds, we're doing 65 right now, you can't even hear it. No drone, no nothing at all. You downshift, get on it though, it has that nice aggressive sound we're used to from Roush mufflers.

That Roush sound that was so popular with 11 through 14 is alive and well for the 15 too. It sounds nice and aggressive when you get on it, but on the highway it's real mild and no drone whatsoever. Installation is also pretty straightforward. Probably take you only around an hour. For the best selection of 2015 Mustang parts, make sure you check out For more install videos like this, make sure you subscribe to our YouTube channel.

Vehicle Fitment

This product will fit the following Mustang years:

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