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

Item 69110
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      Video Review & Installation

      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.



      Roush 403936

      CA Residents: WARNING: Cancer and Reproductive Harm -

      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

      Customer Reviews (100+)

        Questions & Answers

        10 More Questions

        Will It Fit My Mustang

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

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