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Roush Extreme Performance Cat-Back Exhaust (05-09 GT, GT500)

Item 69110
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      Review & Installation Video

      The Roush Extreme Performance Cat-Back System is available for any 2005 to 2009 GT or Shelby GT500 owner, who's looking for a muffler delete style exhaust that has a unique hollow growl, deeper and more aggressive than stock. Since this is a straight pipe design, the cost is kept at an affordable level around the $600 mark, making it easier on your wallet. Installation doesn't require any cutting or modification, so except one out of three wrenches on our difficulty meter, which we'll talk more about later on. Taking a closer look at the sound you just heard from this kit, Roush has put together a super aggressive cat-back that absolutely fits the muscle that the GT500 puts out. Both the Shelby and the GT models get a noticeable change in tone, and that's what makes this kit so unique. It's got the deep growl, but the tone sets it apart from others thanks to the lack of mufflers. Also, contributing to this is the incorporated mid-resonator design here just after the mid-pipe. Together this sound is loud enough to catch all the attention leaving your local car show, while having virtually no drone inside the cabin, because sound is more effectively directed backwards to the system, and out to through the rear. With all that said, I'm giving this four out of five on our loudness meter. It's definitely loud, but I don't think it'll wake as many neighbors as say the Borla Atak or the Corsa Extreme. One of the things people tend to forget when checking out an exhaust system like this is it can actually help slightly improve fuel efficiency. This is simply due to the fact that the engine runs into less air resistance and do it's job, ultimately leading to an increase in horsepower and tork as well, thanks to the higher flow system compared to a conventional one. Roush has this system CNC machine from Mandrel Bends that increase air flow through the 2 and a half inch 409 stainless steel tubing. This material is great for durability, and it's a good choice for those located in wintery weather areas like us here on the east coast since it'll hold it's own against salty roads longer than the aluminized options. To top it off, you'll see the 2 big 4 inch 304 stainless steel polished tips with the Roush logo embedded into the metal. This is definitely a styling bonus for the rear in my personal opinion. This is currently the only full cat-back with a muffler delete design available for the GT and Shelby models on AM. Given the fact it's 409 stainless, and one of the better materials on the market, I would've expected a higher price tag. The lack of mufflers did help to keep the price just about the $600 mark, making this a super affordable way to get some serious volume and tone out of your motor. You want to be heard, but you don't want to wake up the block, or annoy your significant other with the drone, this is definitely a good way to go. The insulation as I mentioned earlier will not be requiring any drilling or cutting or any of that nonsense, so you can expect a direct bolt on job here with simple hand tool like a ratchet, a 15 millimeter socket, as well as some jack and jack stands, or a lift if you have access to one. Overall, this shouldn't take longer than an hour or so in the driveway or garage, so I'm giving it one out of three wrenches on our difficulty meter. You'll obviously want to start off by getting the car in the air and support on jack stands or a lift. Once you're underneath you can unclamp the factory mufflers from the over axel pipes using a 15 millimeter, and then pull them out of there hanger isolators, setting them aside. From here, you can unclamp the over axel pipes from the factory h pipe or after market mid-pipe, if you have one, then set those aside as well. Pick up your new over axels from Roush with the included resonators you see here, and clamp them to the mid-pipe. From here, you can do the same with the muffler delete axel back portion of the system, then hook them into the hanger isolators in the factory locations, and you're good to go. That pretty much wraps up my overview and install. So, if you're the owner of a 2005 to 2009 GT or the lucky owner of a Shelby GT500, you might want to check out the Roush Extreme Performance Cat-Back Exhaust System. You can find it right here at

      Product Information

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


      • Deep Off-Road Exhaust Tone
      • Muffler Delete; Mid Resonator Design
      • 2.5" Stainless Steel Tubing
      • 304 Stainless Steel Tips with Roush Logo
      • Fits 2005 to 2009 GT and GT500 Mustangs


      Aggressive Muscle Car Sound. Let your engine howl with a Roush Extreme Performance Cat-Back System. This innovative Roush exhaust system features a muffler-delete design with resonators mounted directly after the Mid Pipe, that results in increased air flow, and a unique sound, with no in-cabin exhaust drone.

      Quality Roush Construction. Constructed from CNC mandrel bent 2.50-inch diameter stainless steel tubing for a durable long life, the Extreme Performance Cat-Back System features two 304 polished stainless steel 4-inch tips with embossed "ROUSH" logo.

      Application. This Roush Extreme Performance Cat-Back System will fit the 2005 to 2009 GT and 2007 to 2009 Shelby GT500 Mustangs with the factory rear valance.

      Technical Note. Americanmuscle recommends adding the 2005+ Mustang 304 Stainless Steel Exhaust Hanger Kit from the drop down option above, to provide more strength, stability and a cleaner installed appearance. If you have a 2007 Mustang you may need the kit for correct installation.

      Fitment: 2005 2006 2007 2008 2009 Details

      MPN# 403936

      CA Residents: WARNING: Cancer and Reproductive Harm -


      Customer Reviews (100+)

      Write a Review

      Ratings Summary

      4.8 out of 5 overall rating from 100+ customers

      Installation Time: Afternoon

      Installation Cost: $100-$250

      • March 25, 2020

        5 2006 GT - Toylet Installation Time: Less than 1 Hour


        No problems with the installation. The drone associated with the 4.6 is pretty well non-existent with this exhaust. And it has a nice sound when you start letting the revs fall as you downshift. Very happy with it.

        Helpful (1)
      • March 13, 2020

        3 2008 GT500 - JesusR

        Work perfectly, fit great

        Just a little disappointed in the sound but great product overall.

        Helpful (0)
      • February 28, 2020

        5 2009 GT - RyanB Installation Time: Less than 1 Hour

        Great Sound

        I was afraid these would be a bit too loud for my daily driver, and they almost are. HOWEVER, they are really only excessively loud at a very specific RPM (like at 70 MPH going up hill with the windows closed). Any other RPM they sound great, no drone. Nice pops an crackles on the overrun, and they sound fantastic at ANY RPM with the windows open. In the end what made me take the chance with these was all of the reviews I read - pretty much dead on. Do not regret buying them at all, price was right and fit/finish is great. Neighbors might not like the cold start loudness but that only last for about 10-15 seconds...Highly recommend these pipes. BTW, I am running stock cats and H-pipe.

        Helpful (1)
      • February 04, 2020

        3 2002 GT - Likeapos321 Installation Time: Afternoon

        Best sound and loudest

        This was on my 07. I had this paired with an off-road x pipe and wow did it sound great but for $700 I could’ve just bought some slp loudmouths and gotten the exact same sound. Kind of a rip off just for a name brand. Same style resonator as the loudmouths 1 aswell.

        Helpful (0)
      • January 10, 2020

        5 2007 GT500 - Jak147 Installation Time: Less than 1 Hour

        Roush on 07 GT500

        I had a Borla S-Type on before and nothing compares to this! This exhaust is amazing! I love the noise it makes and how aggressive it is. It took about 1-2 hours to install, extremely easy with a lift.

        Helpful (0)
      • December 22, 2019

        5 2005 GT - tgibs2517 Installation Time: Less than 1 Hour

        Awesome exhaust

        This exhaust has changed the whole sound of my car making it sound amazing! It sounds just as I think a mustang should sound!

        Helpful (0)
      • July 05, 2019

        5 2007 GT - Krisa Installation Time: Less than 1 Hour


        Exactly what I was looking for, my mustang sounds 100 better

        Helpful (0)
      • June 27, 2019

        5 2009 GT - JesseL Installation Time: Shop Install Installation Cost: 0-$100

        Great sound

        Went from Pypes Violator Axle-Back to this Roush Cat-Back and the difference was huge. The tone and volume is perfect. Cold starts are pretty loud but overall great.

        Helpful (0)
      • June 22, 2019

        5 2008 GT - Scott Installation Time: Shop Install Installation Cost: $100-$250

        Roush cat-back exhaust system

        Really looks great and sounds really great and very loud!

        Helpful (0)
      • June 22, 2019

        5 2008 GT - Santos Installation Time: Afternoon

        Roush catback

        Sounds amazing.!! I get lots of attention now from people on the way it sounds.! Definitely makes it sound like a muscle car. Very happy with choice of catback. Install was easy nothing to difficult with the roush. Having the right tools and help made it easier. Got done in about 1 hour and half

        Helpful (0)

      Questions & Answers (53 answers)

      5 Top Rated Questions

      What's the loudest exhaust setup I can possibly do available on American muscle

      • Hey Kev, So the loudest exhaust system would consist of longtube headers, an off road x pipe, and a resonated cat back system. Kooks long tubes with kooks off road x pipe, and either a roush extreme, flowmaster outlaw, pypes pype-bomb, or borla atak catback systems to finish the package. Those will be the loudest set ups that we carry.

      Helpful (8)

      Would it fit my v6?

      • You could install this Roush Catback, or any other GT catback of your choice, when combined with the Cut and Clamp X-pipe which I've attached below for you. Essentially, you'd be converting to dual exhaust. The x-pipe will reuse your stock catalytic converters and then bolt up to whichever GT catback you decided upon. Hope this helps!

      Helpful (2) Show 1 more answer

      How much hp will this add to an 05-09 Gt

      • This will not be adding horsepower to an otherwise stock Mustang. When looking at exhaust, the only piece you should really focus on in regards to power are the headers. Everything else will offer little to nothing, but either way it's negligible gains. You should focus on sound with catbacks.

      Helpful (1)

      Will this system pass California Smog inspection?

      • This Roush Extreme Performance Cat-Back System will not alter emission outputs and therefore will not single-handedly cause a smog inspection failure.

      Helpful (1)

      Do I have to Change my mid pipe? I have been looking for a while on trying to make my '07 California Special louder. I have listened to a countless amount of sound clips trying to figure out what I like best. After hearing this system on the Internet I think I found what I have been looking for. I was wanting to know if I needed to change to a different mid pipe. I love the deep muscle car note with the h pipe over the race car growl with the x. I hope to keep the h for this system. Will I be able to?

      • You do not have to change your mid-pipe for this particular catback system (I have this exact one in my car). You will gain a louder sound, especially because this system has resonators (that don't drone!) and no mufflers. However, if you want louder, deeper sounds, replacing your mid-pipe is a strong suggestion. Either go with an H-pipe or Pro-Chamber (even a little deeper sounding than H). Even better, if your state allows it, go sans catalytic converters (ie. off-road). You get a louder sound, cut weight from the existing (read: heavy) exhaust system, and also increase MPG as the car can breath and flow exhaust better. The choice is, of course, yours but at the end of the day, you can keep your existing mid-pipe as is.

      Helpful (1) Show 2 more answers
      10 More Questions
      I have an 06’ v6 mustang will this be compatible? 1 answer
      I have an 08 v6 mustang and was looking to get the X Pype cut and clamp and the Roush extreme performance Cat-Back Exhaust. Would these two parts combine and work? As well as sound good? 1 answer
      I have an 08 v6 mustang and was looking to get the x Pype cut and clamp and the Roush extreme performance Cat-Back Exhaust. Would these two parts combine and work? 0 answer
      will these work with long tube headers? 1 answer
      What is the diameter of the resonator? 1 answer
      will this PA state inspection? 1 answer
      will this exhaust pass state inspection in PA.? 1 answer
      Will this cat-back system fit with bbk longtubes and a bbk off-road xpipe? 1 answer
      Will this cat back system work with the kooks long tube headers matched with the kooks catted xpipe? 1 answer
      Can this be used with the roush rear valance square tips? 1 answer

      Installation & What's in the Box

      Installation Info

      What's in the Box

      • (2) catback pipes with mufflers
      • (2) Muffler assemblies
      • (2) Clamps

      Tech Specs

      Cat-Back Exhaust Specifications
      Piping Material: Stainless Steel Tip Material : Polished 304 Stainless Steel
      Piping Size: 2.5" Tip Size: 4"
      Muffler Type: None / Resonator Fitment: 2005-2009 GT & GT500 Mustangs

      Will It Fit My Mustang

      • Bullitt - 08, 09
      • GT - 05, 06, 07, 08, 09
      • GT500 - 07, 08, 09

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