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Roush Axle-Back Exhaust (15-21 EcoBoost w/o Active Exhaust)

Item 387040A
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      Video Review & Installation

      What's up, guys? Stephanie with, and this is my review of the Roush axle-back exhaust fitting 2015 and up EcoBoost Mustangs. The Roush axle-back is going to be a good option for the S550 EcoBoost owners out there that are looking for a more aggressive, raspy exhaust note from an axle-back system. This isn't necessarily an over the top or too loud of a system, but it's definitely not a quiet or toned down system, either. This is a perfect option for guys that are looking for something loud and something that's going to open up some exhaust flow and give a meaner sound than the factory exhaust. The axle-back is designed to open up sound and exhaust flow and ultimately power. This axle-back does have Roush's hollow open chambered mufflers that are straight through mufflers, and it's on the louder side. This is a full stainless steel axle-back and it's also mandrel bent. You're looking at 4 inch polished stainless steel tips for out back as well that are chrome flashed. The stainless steel is always a great option for cars that see all different types of road conditions because it offers great corrosion resistance. From the EcoBoost, you can hear that it idled. The axle-back is deeper than the factory exhaust and it's also louder. As the RPMs climb the axle-back loses some of its deepness and the axle-back gets louder. There's a lot of raspiness and pop to it, but the axle-back's made for that. It increases in volume. It doesn't really get quiet like some other axle-backs do which is what makes it perfect for those that are not looking for a tame exhaust. Speaking of things like volume and raspiness, I will admit that this axle-back may have a little bit of sound distortion to it, especially in the higher RPMs. That is something that's normal even with a factory exhaust and high RPMs. Some people love a raspy note and others try to avoid it. This system has a lot of that. If you're not looking for those qualities then there are some other better options for you on the site. Like most aftermarket axle-backs, this one's going to open up some of that nice turbo noise in the EcoBoost. It has better flow, so the turbo noise is very noticeable with this axle-back. You can hear the turbos full and you get a lot of the blow up noise as well. With all this being said, you have to keep in mind that the EcoBoost is a four cylinder turbo car. It's not going to sound like a V8. It's going to have a different sound than the V6 even. You can't really make it sound identical to a V8. There are, however, other exhaust options that can give you a smoother sound that resembles more of a V8. Don't be discouraged if you're an EcoBoost owner and you aren't into this axle-back. Overall, this is a deep sounding system that has a lot of raspiness and popping to it. I wouldn't call it quiet or tame. This is just an axle-back, so keep in mind that it can get even louder with a midpipe and headers. With that being said, I'm going to give it a solid three or four out of five on the loudness scale. At the end of the day, though, no matter if you love this sound or hate it, it really all depends on what you're looking for and what you like. Luckily, there are quite a few options that are out there. When we start to look at price, we see that this axle-back is going to be on the less expensive side of things. It costs right about $550. Some of the more expensive competition is hitting the $800 or $1000 or even $1200 price point. The budget friendliest are coming in halfway through the $300 mark. You're going to be looking at the typical cut and clamp design with the install with this axle-back like all other axle-backs. I'm going to call this a two out of three wrenches on the scale just like I do with all other axle-backs, but just because of the cutting that's involved. It's nothing difficult. I would just recommend some eye protection and a fresh blade to make the cutting easier. Overall, you're looking at about two hours to get this all done. A lift would certainly make things easier for you here, but the job can be done on stands as well if you don't have access to a lift. Cutting the factory axle-back isn't hard. I would just be sure to measure twice and plan and mark where you'll be cutting so you don't make a mistake. The new axle-back will come with four new clamps for you, two for the tips and two for the axle-back itself so you don't have to worry about that. When you go to install your new setup, it would probably be easiest to leave everything loose until you have it all lined up and then tighten it down. Overall, the Roush axle-back is a great option for those looking for a louder and raspy sounding system. It's an open chambered muffler design. It's made from 304 stainless steel. It has 4 inch chrome flashed stainless steel tips. You can check this axle-back out some more online for yourself. For all things Mustang, keep it right here at

      Product Information

      Features, Description, Reviews, Q&A, Specs & Installation


      • Aggressive Raspy Exhaust Note
      • Unique Open-Chambered Muffler Design
      • 304 Stainless Steel Construction
      • Full Mandrel-Bent Tubing
      • 4" Round Stainless Steel Tips w/ Chrome Flashing
      • Not Compatible with Active Exhaust
      • Fits 2015-2021 EcoBoost Mustangs


      Aggressive Raspy Sound. Let everyone know your EcoBoost Mustang has arrived with the aggressive raspy sound of this high performance Roush exhaust. This innovative new Roush exhaust system features a hollow open chamber muffler that results in increased air flow and a unique sound, with no in-cabin "boom" normally found with performance exhaust at cruising speeds.

      Quality Roush Construction. Constructed from mandrel bent 304 stainless steel for a durable long life, the Roush axle-back exhaust system features two unique open chambered mufflers with 304 stainless steel 4" tips. The 4" tips are finished with a new chrome flashing process that is resistant to discoloration due to exhaust heat.

      Cut & Clamp Installation.
      The installation of this Axle-Back Exhaust requires cutting and removing the stock muffler assemblies, and clamping the new muffler assemblies in place. Clamps and instructions are provided.

      This Roush Performance Axle-Back exhaust system is designed to fit the 2015-2021 EcoBoost Mustangs without the Active Valve Exhaust.

      Fitment: 2015 2016 2017 2018 2019 2020 2021 Details

      Roush 421837

      CA Residents: WARNING: Cancer and Reproductive Harm -

      Installation & What's in the Box

      Installation Info

      What's in the Box

      • (1) Muffler assembly - Driver Side
      • (1) Muffler assembly - Passenger Side
      • (2) Tips
      • (4) Clamps

      Tech Specs

      Axle-Back Exhaust Specifications
      Piping Material:304 Stainless Steel Tip Material :304 Stainless Steel with Chrome Flashing
      Tip Size:4"Muffler Type:Open chambered
      Fitment:2015-2021 EcoBoost

      Customer Reviews (100+)

        Questions & Answers

        10 More Questions

        Will It Fit My Mustang

        • EcoBoost - 15, 16, 17, 18, 19, 20, 21

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