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Flowmaster Outlaw Cat-Back Exhaust (05-10 GT, GT500)

Item 393798
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      Review & Installation Video

      You should check out the Flowmaster Outlaw cat-back if you're looking for a budget-friendly, stainless steel cat-back that's going to be loud. The cat-back features the Outlaw mufflers, which are known to deliver on sound, and they're some of the most affordable on the site at this time. When it comes to the install, you can expect this to take [you] an hour or two, and it's going to be a one out of three wrenches on the difficulty meter. Sound is going to be one of the most important things here when it comes to this system, and the Outlaw mufflers are race-oriented mufflers that are more resonator tubes than actual mufflers. These produce a sound that has a low decibel, but it rumbles and has a good amount of volume to it. Even though these are race-style mufflers, Flowmaster does tune the mufflers, so you're not just going to get a ton of noise. The tuned sound means that you'll get a good, controlled sound on the outside of the car, and little to no drone in the interior, which will be nice for those daily drivers. This cat-back doesn't produce a high-pitched raspy sound. It does have some popping on the decel note, so you're not looking at a flat sound. Overall, I'd rate this cat-back as a four out of five on the loudness scale, with one being a quiet upgrade and five being a very loud upgrade. Now, just make sure you keep in mind that if you ever change your headers or your mid-pipe down the road, this could open up even more noise for you. As far as materials, you're looking at 409 stainless steel for the majority of this system here, and 304 stainless steel tips. The fact that the tips are stainless steel means that they're going to keep that nice polished look to them, even over time. The entire cat-back is mandrel-bent, and it's two and a half-inch most of the way. So it'll bolt right up to your factory mid-pipe. The mufflers, which are coated black, have a three-inch diameter, and the tips are four-inch. Price-wise, you can expect to pay just over the $600 mark for this cat-back. This isn't the least expensive option out there, but it is one of the most affordable, especially when it comes to stainless steel options. If you're really on a budget, though, Pypes does make the Pype Bomb Super System, that's loud like this cat-back is, for about $50 less. This is a direct bolt-on item, so you're looking at a very easy install. I'm going to call this a one out of three wrenches on the scale when we look at difficulty. Overall, you're looking at about one hour to get this all done. A lift would certainly make things easier for you here, but the job can be done on jack stands as well, if you don't have access to one. All that you're really going to need is a socket set when it comes to tools. This cat-back will come with new hangers and all new clamps for you, so no need to transfer over anything from your stock exhaust. The whole cat-back can be dropped as one big piece, so an extra set of hands can really help here. When you go to install your new setup, it very simply bolts right up into the stock location, so you won't have to cut or modify anything. It'll probably be easiest to leave everything loose until you have it all lined up, and then tighten it down. That's going to be it for the Flowmaster Outlaw cat-back exhaust, fitting the 2005 through 2010 GT and GT500. But you can check it out more online right here at

      Product Information

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


      • Outlaw Series Cat-Back
      • Constructed from 409 Stainless Steel
      • Fully Mandrel Bent 2.5” Tubing
      • Two Outlaw Black Mufflers
      • 4" Polished 304 Stainless Steel Tips
      • All Clamps and Brackets Included
      • Fits 2005-2010 GT and GT500 Mustangs


      Look Great and Sound Great. Your 2005-2010 GT or 2007-2009 GT500 looks great rolling down the street. But if you're not getting that legendary Mustang rumble to go along with those great looks, here's the answer. The Flowmaster Outlaw Cat-Back Exhaust System provides that incredible, low decibel rumble that makes Mustang owners and admirers so loyal. To top it off, the 4” diameter polished stainless steel tips makes your Pony look as powerful as it feels when you're out enjoying the ride or just taking a quick peek while she's waiting in the garage.

      Specifications. The Outlaw Cat-Back Exhaust features 2.5” diameter, mandrel bent tubing constructed from race proven, 409 stainless steel. This Cat-Back is finished off with two black outlaw style mufflers and two 4” polished stainless steel tips embossed with the Flowmaster Logo. All Flowmaster exhaust systems are tuned to make sure the sound is great both outside and inside your ride.

      Installation. The Cat-Back Exhaust System comes with all clamps and hangers for a complete upgrade from your factory cat-back. This Flowmaster system uses factory mount locations, making installation very straight forward. The kit is covered by Flowmaster's Lifetime Warranty to make this upgrade an easy decision.

      Application. This Flowmaster Outlaw Cat-Back Exhaust is specifically designed to fit 2005-2010 GT, Bullitt and GT500 Mustangs equipped with the 4.6L and 5.4L engines.

      Fitment: 2005 2006 2007 2008 2009 2010 Details

      Flowmaster 817515

      CA Residents: WARNING: Cancer and Reproductive Harm -


      Customer Reviews (27)

      Write a Review

      Ratings Summary

      4.6 out of 5 overall rating from 27 customers

      Installation Time: Afternoon

      Installation Cost: $100-$250

      • May 07, 2020

        5 2010 GT - mechanikyle Installation Time: Afternoon

        Very satisfied

        Sounds good, def loud but not rediculous. Probably with headers and cat delete would be very loud, mine is mostly stock now though. Taking the old off was harder than install.

        Helpful (0)
      • February 07, 2020

        5 2009 GT500 - MitchellW Installation Time: Less than 1 Hour

        Loud is GOOD

        Changed out my OEM exhaust for Flowmaster Catbacks with Outlaw muffler. The sound is incredible. Deep and rumbles at idle. Sound awesome when you step on the gas. Thre isd a little drone at about 2500-3000 RPMS, but nothing thzt I can't live with.

        Helpful (3)
      • January 24, 2020

        5 2010 V6 - Captive11 Installation Time: Shop Install Installation Cost: $100-$250

        Honestly amazing

        Love the sound. Fit perfectly. Made my V6 sound a whole lot better

        Helpful (3)
      • December 02, 2019

        3 2010 GT - Anonymous

        Could’ve been happier

        Sounds great but one of the mufflers did not line up properly. One of the welds on the tailpipe was at least a half inch longer than the other side. Three-quarter would be more like it. The exhaust hangers also needed to be bent in order for proper fitment.The options to resolve this through customer service involves sending back the entire exhaust system. It was already installed on the car. Or purchasing a whole Nother system with my own money taking out the good muffler. And then shipping the entire system back. They did give me a credit for my trouble but I’m stuck with looking at a uneven tailpipe every day

        Helpful (3)
      • October 24, 2019

        5 2007 GT - AdamF Installation Time: Afternoon

        Sounds great

        Choose these because I heard they were the loudest on the market. They sound great! Install took me an afternoon.

        Helpful (3)
      • September 22, 2019

        1 2008 GT500 - Sam1985 Installation Time: Less than 1 Hour

        Way to Raspy.

        Wouldn’t recommend this exhaust it’s honestly just way to raspy. You can’t even hear your supercharger with these on.

        Helpful (4)
      • April 26, 2019

        5 2010 GT - needy Installation Time: Shop Install Installation Cost: $100-$250

        Loud and Good Tone

        Love every minute of this exhaust. Very loud but I’m starting to get used to it so I may need an upgrade.

        Helpful (3)
      • April 13, 2019

        5 2008 GT - 2008P51Roush Installation Time: Less than 1 Hour

        Flowmaster outlaw review

        I just finished with the installation of my Flowmaster Outlaw Exhaust and i couldn't be happier. The fit and alignment of the exhaust components was great, hanger rods lined up perfectly with the original and the sound OMG does this sound great. A really nice throaty growl at idle and a nice sharp rap when you get on it.

        Helpful (3)
      • December 07, 2018

        5 2008 GT - Tugger Installation Time: Afternoon

        Great sound!

        Another great Flowmaster product. Quality construction and just the sound I was looking for on my 2008 Mustang GT.

        Helpful (6)
      • July 15, 2018

        5 2007 GT - JoelW Installation Time: Shop Install Installation Cost: $100-$250

        Aggressive and loud

        Love the sound. I wake up the neighborhood on every cold start. I turn heads every time I drive through the city. No cabin drone. Very loud. My car speaks for itself and will not shut up. She knows what to say and how to say it.

        Helpful (12)

      Questions & Answers (12 answers)

      5 Top Rated Questions

      What's the Comparison of these Flowmaster Outlaws to the Magnaflow Competition Exhaust Sound?

      • The outlaws offer one of the loudest exhaust tones. The outlaws are more comparable to the Roush and Corsa Xtreme exhausts in terms of how loud the exhaust is. The Magnaflow will offer more of a mild exhaust tone.

      Helpful (1)

      I have a 2007 GT, will this work with everything stock and without deleting my cats? I plan on purchasing the Pypes Catted X-Pipe later on but wanted to see how these fit and sounded first.

      • This cat-back is going to install onto 2005-2010 GT and GT500 model Mustangs without the need for other modifications.

      Helpful (1)

      I want to upgrade to long tube headers and off road H-pipe. What can I use or are there specific combinations?

      So if I get these an say there to loud I don’t like them I currently have the axle back MBRP on my mustang an just wanted to switch the axel backs would I have to put the stock exhaust back on to fit my MBRP

      Are the flowmaster outlaw cat-back louder than the flowmaster outlaw axleback?

      • Generally speaking, when comparing a cat-back and axle-back of the same model & manufacturer, the cat-back will be the louder of the two.

      Helpful (0)
      Post Your Question
      7 More Questions
      Will this fit with a Pypes x pipe ? 1 answer
      Will this work with the set of Pypes long tube headers and shorty X pipe I just bought ? 1 answer
      Will this fit my v6 mustang? 1 answer
      What aftermarket X pipes and headers would work well with this system? 1 answer
      Will this hook up to my factory H pipe on my 2008 GT? 1 answer
      For 2010 Gt can i hook these right up to the existing h pipe, have to wait to get catted x-pipe and headers. 1 answer
      what will i need to do to apply this exhaust to my 07 v6? 1 answer

      Installation & What's in the Box

      Installation Info

      What's in the Box

      • (1) Right Muffler Assembly
      • (1) Left Muffler Assembly
      • (1) Right Over-Axle Pipe
      • (1) Left Over-Axle Pipe
      • (2) 2.5 in. Band Clamps

      Tech Specs

      Cat-Back Exhaust Specifications
      Piping Material:409 Stainless Steel Tip Material :Polished 304 Stainless Steel
      Piping Size:2.5"Tip Size:4.0"
      Muffler Type:Straight ThroughFitment:2005-2010 GT, Bullitt and Shelby GT500

      Will It Fit My Mustang

      • Bullitt - 08, 09
      • GT - 05, 06, 07, 08, 09, 10
      • GT500 - 07, 08, 09, 10

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