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Roush Quad Tip Active Axle-Back Exhaust (15-17 GT Premium)

Market Price $2,689.99 You Save 1% ($30.00)
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  • Item 389790
  • MPN# 421924

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Fastback Convertible
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Features & Details

  • ROUSH Active Axle-back Exhaust System
  • Select Between Touring, Sport, Track and Custom Exhaust Notes
  • Custom Programming with Included WiFi OBD2 Interface and Roush iOS App
  • Unique Open-Chambered Muffler Design
  • 304 Stainless Steel Construction
  • Full Mandrel-Bent Tubing
  • 4" Stainless Steel Quad Tips With Chrome Flashing
  • Cut & Clamp Installation
  • Fits 2015-2017 Premium Package GT Mustangs equipped with a Roush Rear Valance
ROUSH Active Exhaust System. Take total control of the volume and performance of your S550 GT Mustang with a ROUSH Active Exhaust system. Roush's proprietary Active Exhaust system ties directly into your Mustang's powertrain control module, opening and closing the mufflers valving based on throttle position.

Four Distinct Exhaust Sounds. The ROUSH Active Exhaust System includes a center console mounted selector knob that allows you to easily switch between four different sound modes on the fly. Choose from Touring, Sport, Track, and Custom.
  • Touring. The Touring mode closes the mufflers valves completely keeping the exhaust volume to an absolute minimum.
  • Sport. The Sport mode keeps the exhaust quiet during normal driving conditions. Accelerator position and vehicle speed are used to determine valve position, opening up under acceleration for a more aggressive sounding ride.
  • Track. The Track mode is wide-open. This mode keeps the exhaust tailpipe valves fully open at all times and doesn't restrict the raw sound of your Mustang. This mode is intended for track use and is not legal for street use.
  • Custom. The Custom mode lets you create a custom sound map with the included WiFi OBD2 interface and ROUSH iOS application to personalize the exhaust sound to your own tastes. With the app you gain full control over the position of the valves based on vehicle speed, rpm and accelerator position. Download the free ROUSH Active Exhaust App for iOS - Here

Quality Roush Construction. Constructed from fully mandrel-bent 304 stainless steel for a durability, corrosion resistance and long life, the Roush Axle-Back Exhaust features two unique open chambered mufflers with 304 stainless steel dual wall quad tips. The 4" quad 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, removing the factory muffler assemblies and clamping the new muffler assemblies in place. Clamps, hardware and installation instructions are provided.

Application. This Roush Quad Tip Active Axle-Back Exhaust System is designed to fit fastback or convertible 2015-2017 GT Mustangs equipped with the factory Premium Chassis Package (Trim Levels: 400A/401A) and will require the use of the Roush Rear Valance 421894 or 421919 for proper installation (valance sold separately).

Download the Roush active exhaust app instructions - Here

Fitment: 2015 2016 2017 Details

What's in the Box
  • (1) Exhaust Pipe with Valve – LH
  • (1) Exhaust Pipe with Valve – RH
  • (1) Flashed Controller, Active Exhaust
  • (1) Vehicle Ready Wiring Harness 
  • (1) OBDII Active Exhaust Programmer
  • (1) Hardware Kit – Active Exhaust
  • (1) Switch, Mode Selector
  • (1) Switch Plate, Metal with Engraving
  • (1) Switch Bracket
  • (2) Bolt – M4 x 0.7 x 10
  • (2) Push Nut – 3/16” 
  • (3) Washer – M4 Nylon 
  • (7) Zip Tie with Edge Clip
  • (1) Knob, Knurled Style
  • (1) Set Screw – M3 x 0.5 x 6 
  • (1) J-Clip – M6  
  • (1) Bolt – M6 x 31 HEX
  • (2) Foam Tape 30 mm x 35 mm x 7.9 mm
  • (1) Micro Fuse – 10 AMP   
  • (20) Zip Tie – 7”  
  • (1) Multipurpose O-Ring, 5.6 mm
Installation Info
Tech Specs
Will it fit my Mustang?
  • GT - 16, 15, 17

People Who Bought This Item Also Bought

Most Helpful Reviews

Make sure to order the correct one!!!

Awesome product. Looks great, sounds even better! One important thing to note when you order, if also ordering the matching Rear Valance: It will ask you to choose from: "Rear Valance with sensor ...

Read More
Helpful (1)

Sounds Great but Flawed

I have an Active Exhaust system on my 2015 Roush Stage 3 and I have mixed feelings. When it works, it sounds great, but over the past 18 months it has been into the dealer for repair work 3 times, and ...

Read More
Helpful (1)

Overall Rating 4.2 out of 5 stars
Read All 4 Reviews

Customer Photos

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4 Questions / 5 Answers

Ask a Question

Will this kit fit in the gt350 rear valance, or be adaptable to fit onto the gt350's quad tip kit for the normal GT premiums? that valance looks night and day better and would give people more options.


  • From the given image of this product by American Muscle and Roush Performance websites, I will say this muffler definitely will fit the GT350 rear valance since the sizes seemed to fit. I have a complete FRPP GT350 Sport exhaust kit. GT350 valance has the end tips mounted on the valance and i deem that the roush muffler will fit if the roush end tips is not installed. Actually I am waiting on the shipment of this Roush exhaust and I will try then I can give this question a more reliable answer.


Show 1 more answer Helpful (1)

To whom it may concern, Wondering what the horse power increase will be once installed. I see from the reviews that people love the sound but I am more interested in lowering the back pressure and increase horse power. Regards TK


  • Doing an Axle-back or cat-back exhaust will not really gain you any horsepower. These would simply be for sound. If you are looking for performance you will want to check out long tube headers!


Helpful (0)

I have one of these. What does it mean when the orange light comes on?


  • Hi,I'm sorry to hear you are having problems with your active axle-back please call or send us a email so we can help you out with your problem.

    Chris J

Helpful (0)

will this fit a mustang gt 2016 not premium


  • This exhaust system is exclusively designed for 2015-2017 GT Mustangs that have the Premium Chassis Package. They also require the Roush rear valance (either item #421894 or #421919) for proper installation.


Helpful (0)

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Customer Reviews (4) Write a Review

Overall Rating 4.2

out of 5 stars

Installation Time:Weekend

  • Loudness / Volume 5 5
  • Exhaust Note 5 5
  • Fit & Finish 4 4
  • Bang For Your Buck 4 4

  • 3/5

    June 06, 2017

    Sounds Great but Flawed

    I have an Active Exhaust system on my 2015 Roush Stage 3 and I have mixed feelings. When it works, it sounds great, but over the past 18 months it has been into the dealer for repair work 3 times, and still fails (it's in again now). It will work for a while, then just fails (and when it fails, it fails to the quietest setting, which isn't really the point!). Also, there is NO Android support for the app to control custom mode, and, per Roush, there is absolutely no plan to ever add Android support, so if you want to play with the custom settings, and use Android, think twice...


    Year: 2015 Submodel: GT

    Helpful (1)

  • 4/5

    August 30, 2016

    Make sure to order the correct one!!!

    Awesome product. Looks great, sounds even better! One important thing to note when you order, if also ordering the matching Rear Valance: It will ask you to choose from: "Rear Valance with sensor holes" or "Rear Valance w/o sensor holes" I wasn't sure, so I went and took a look, and while I did notice I have back up sensors, they were not located in the rear valance, (actually located in the bumber several inches above it). Assuming Ford made other models that had the back up sensors located IN the valance...I indicated "Rear Valance w/o sensor holes" so I would not have 4 holes in my new valance unused. So after dismantling the back end of my car, and having already cut up my bumper to fit the new valance(yes you will need to do that to install this)...I then discovered that the new valance is taller than the old, and installs OVER the back up sensors on the actual bumper. Noooow I understand... ;-) Being my only vehicle, needing to get to work the next day, and with my old one not able to go back on due to all the cutting...I had no choice but to install it over the sensors. The backup sensors now toss up an error message on my screen every time I back up, and of course not functioning. With that said I absolutely love the product itself. It just stinks that having already bought it once, now I have no choice but to save up another $250 bucks to order the correct one, and spend another half day making the swap. So please take heed! If you have backup sensors, (even if they are not located in your existing rear valance) get the one with the holes for them, as it will cover them up!!! Note to AM: A loyal customer for years now modding two mustangs, and have nothing but great things to say about AM, you guys rock! But please do others a favor and make a note about the back-up sensors on the product page...that it WILL cover the existing even if NOT located in the existing valance but above it! My bad for overthinking I guess, and I'm sure some others maybe laughing over this post :-), but would hate to see someone else make the same mistake! Once my piggy bank is full again...I'll be placing my order for the correct one. Until then "ERROR: BackUp sensor FAIL"...but will sound good while I clear it each time ;-)


    Year: 2015 Submodel: GT

    Helpful (1)

  • 5/5

    Installation Time: Weekend

    July 24, 2017


    YouTube videos don't do this exhaust justice. Roush says it takes 9 hours worth of labor and that's pretty accurate. Ford took 12 hours to install this system along with the Roush C pipe (which I recommend doing all at once). It's definitely the most expensive system for the S550 but you definitely get the best bang for your buck. Being able to turn down your exhaust when it's late at night near your house or when you see a cop sitting at the light has already been worth it.


    Year: 2015 Submodel: GT

    Helpful (0)

  • 5/5

    April 13, 2016

    Great Value and Overall Great Quality

    Great product, worth the price and then some. Sounds amazing!


    Year: 2014 Submodel: GT

    Helpful (0)

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