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Flowmaster Outlaw Cat-Back Exhaust (15-17 GT Fastback)

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Market Price $1,115.99 You Save 12% ($130.04)
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  • Item 387145

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    Features, Video & Details

    • Super Aggressive Flowmaster Outlaw Sound
    • Durable 409 Stainless Steel Construction
    • 3" Mandrel-Bent Tubing
    • 4" Polished Stainless Steel Tips
    • Includes X-Pipe and Two Flowmaster Outlaw Mufflers
    • Fits 2015-2017 GT Fastback Mustangs

    Review & Installation Video

    Review & Install Video

    Hey everybody, I'm Justin with AmericanMuscle.com and welcome to my quick breakdown of the Flowmaster Outlaw Series Catback Exhaust System, available for your 2015 Mustang GT. As you all just heard, the Outlaw's going to deliver that signature, aggressive Flowmaster sound, thanks largely in part to the patented Outlaw Series mufflers here, one of the loudest offered by Flowmaster, in addition to the removal of the factory resonator. The Outlaw Series mufflers here were actually born and bred for racetrack purposes, where the demand for a lightweight, free-flowing muffler was needed, to tame those crazy volume limits of the open headered sprint cars. Now, this thing became so popular that Flowmaster started incorporating it into some of their more mainstream, consumer exhaust systems, and as a result, it's been one of their top sellers ever since. Replacing that big, goofy suitcase-style resonator here, you're going to find Flowmaster's patented scavenger-style crossover pipe, which is going to take the place of a more traditional X or H pipe. Now, according to Flowmaster, this thing actually produces a little bit more low-end torque than some of those more conventional mid-pipe designs, and it's something that you're going to find with the majority of the Flowmaster Catbacks available for your Coyote-powered Mustang. Getting into some of the details here with the Flowmaster Outlaw Series Catback, you're going to find a full 100% stainless steel construction throughout, three-inch mandrel bent tubing, in addition to these Outlaw Series mufflers here, which as you can see, are done up in the Flowmaster traditional black. Finally guys, four-inch slash cut tips here, embossed with that Flowmaster logo. Unlike the majority of other catback offerings for the 2015 Mustang, there is a small amount of cutting needed to get the Flowmaster Outlaw Series Catback bolted up to your ride. So with that said, be prepared to break out the Sawzall and the eye protection when it comes time to get down to business. Thanks to Flowmaster's detailed instructions, they lay out everything where you need to cut, and you can expect to be making noise in less than three hours from start to finish. So if you're one of the many Mustang owners out there who swear by the Flowmaster name, then be sure to check out the aggressive sounds of the Outlaw Catback for your GT right here at AmericanMuscle.com.

    Super Aggressive Flowmaster Sound. Give your coyote powered S550 Mustang Fastback that unmistakable Flowmaster sound with the Outlaw Series Cat-Back exhaust system from AmericanMuscle. This system improves exhaust flow using Flowmaster's race-oriented style Outlaw mufflers for that super, aggressive exhaust note your high powered Pony deserves.

    Race Car Growl. The included X-Pipe not only helps increase power, but it also adds a loud raspy, race car growl to the sound of your exhaust with its modern "X" crossover pipe design.

    Stainless Steel Construction. Constructed from durable 3" 16 gauge 409 stainless steel tubing for it's corrosion resistant properties the Flowmaster Outlaw Cat-Back features two race-oriented mufflers with massive 4.0" diameter polished stainless steel tips for impressive muscle car looks and sound. As an added bonus, the tips are embossed with the "Flowmaster" logo for true custom styling.

    Application. This Flowmaster Outlaw Series Cat-Back exhaust system is designed to fit the 2015-2017 GT Fastback Mustangs equipped with the coyote 5.0L DOHC V8 engine. Not compatible with convertibles. Reuses the stock hangers for installation.

    Fitment: 2015 2016 2017 Details

    MPN# 817734

    CA Residents: WARNING: Cancer and Reproductive Harm - www.P65Warnings.ca.gov

    What's in the Box
    • (1) Right muffler assembly
    • (1) Left muffler assembly
    • (1) X pipe assembly
    • (1) Right intermediate pipe
    • (1) Left intermediate pipe
    Installation Info
    Tech Specs
    Cat-Back Exhaust Specifications
    Piping Material: 409 Stainless Steel Tip Material : Polished Stainless Steel
    Piping Size: 3" Tip Size: 4.0"
    Muffler Type: Straight-through Fitment: 2015-2017 GT Fastback
    Will it fit my Mustang?

      Customer Photos (12) Submit Your Photo

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        Questions & Answers (15)

        5 Top Rated Questions

        Will this setup bolt on to kooks long tube headers 1 7/8 off-road catless headers?

        • Yes, the long tubes have the correct adapter pipes attached already so you will be fine.

        Helpful (2)

        I have put this exhaust in my 2016 mustang 5.0, and I have noticed that my fuel economy drop down by half, is that normal or do I need something to fix this like a good air intake kit ?

        • A cat-back exhaust will not play any part in fuel consumption. Due to the change in the exhaust sound, that can make you stay in the gas longer than you normally are but cold air intakes along with a tuner can be a good remedy for fixing fuel consumption.

        Helpful (1)

        I am looking at getting an S550 Mustang soon and I had this same catback on my 2013 GT before trading it. The issue I had with the outlaw is that it produced a horrible drone around 1900-2000rpm. Does this set up still have that same drone?

        • I have had this catback system on my '15 GT for ~9 months and I couldn't be happier, but yes, this does have a noticeable drone around that rpm range.

        Helpful (1) Show 1 more answer

        For S550: I have read on forums that cat back GT exhausts fit directly on a v6. Is this true?

        Ever since this was installed onto my 2015 Mustang GT Premium i have been throwing a CEL for Random Multiple Cylinder Misfires and misfires on cylinders 3, 5 8. Whoever owned this before me installed a C L intake (I think the tune required) but possibly didn't tune the car. Did this exhaust throw it over the edge and now i need to tune car to fix issue? I know this light never came on prior to this install....

        • This should not require a tune and we would recommend having the vehicle looked into directly by a local shop in your area in order to verify the issues with whatever codes are being thrown.

        Helpful (0)
        Post Your Question
        10 More Questions
        Can an H Pipe be used instead of an X Pipe for this product? And do you have any recommendations on a compatible H Pipe if so? 1 answer
        If I get an x-pipe with for my v6 mustang can I get a shop to weld this gt exhaust to my 2017 v6 mustang? 1 answer
        any horse power gain from a 3in cat back 1 answer
        Will I have to do some cutting for this to fit my 15 mustang? I saw two people comment in the reviews saying that they had to. 1 answer
        Will this fit on a European spec GT Fastback, the right hand drive model? 1 answer
        Can this exhaust fit with long tube headers and if so what headers will fit this? 1 answer
        Is an o2 extension kit required for this catback? 1 answer
        Can anyone recommend a good set of headers that would compliment this exhaust? Thanks 1 answer
        Will this setup bolt on to a set of long tubes?? 1 answer
        Does this exhaust require a tune? I know its always recommended, but last time my x pipe was really raspy, and after the tune it calmed down. Wondering if this is the same case. Thank you 1 answer

          Customer Reviews (49) Write a Review

          Overall Rating 4.7

          out of 5 stars

          Installation Time:Full Day

          Installation Cost:$100-$250

          • Loudness / Volume 5 5
          • Exhaust Note 4.829787 4.8
          • Fit & Finish 4.702127 4.7
          • Bang For Your Buck 4.723404 4.7



          • 3/5

            Installation Time: Less than 1 Hour

            August 16, 2019

            2 year review, great sound, terrible drone.

            So I actually got this exhaust as a little extra when I purchased my Mustang pre-owned. I've had the car for 2 years now with this exhaust set up on it and my time with it is coming to an end. While I love this exhaust with as much highway driving I do I spend a considerable amount of time in 6th gear cruising, the drone has finally got to me. Having a conversation in the car can be tough and your only real option sometimes is to drown it out with loud music. Overall great exhaust, the note is fantastic with a deep muscle car tone at low rpms that opens up when you get on it. It's definitely a sound that breaks necks and I've gotten many compliments from it. The drone is my only complaint but you get what you get, Flowmaster hasn't earned it's nickname "dronemaster" for no reason. Fantastic exhaust, bad drone. I'd still recommend it.

            Lee

            Year: 2016 Submodel: GT

            Helpful (0)

          • 5/5

            Installation Time: Full Day

            April 23, 2019

            Give Yourself a Presence

            The product was a bit difficult to install. But it sounds great and is very loud. If you dont have a soundproof garage make sure the neighbors like you before purchasing.

            TerryR

            Year: 2017 Submodel: GT

            Helpful (0)

          • 4/5

            Installation Time: Full Day

            February 28, 2019

            Very loud, classic mustang sound

            Great exhaust. Has drone, a lot of it. If you don’t mind sacrificing drone for exhaust sound you won’t be disappointed. Sounds like the 2011-2014 GTs

            Tiogioo

            Year: 2016 Submodel: GT

            Helpful (1)

          • 5/5

            Installation Time: Full Day

            January 26, 2019

            Loud and mean

            It took a day to instal and it was well worth it. She is loud and mean with every shift. Everytime im at a red light people always give me compliments.

            RobertS

            Year: 2016 Submodel: GT

            Helpful (3)

          • 5/5

            Installation Time: Less than 1 Hour

            January 05, 2019

            Great buy!

            Loud and has slight drone but doesn’t bother me any . Going to be hated in my area when I install long tubes in the summer . No fitment issues, my friend and I had it done in about a hour .

            Chris

            Year: 2016 Submodel: GT

            Helpful (4)

          • 5/5

            Installation Time: Shop Install

            Installation Cost: $100-$250

            October 24, 2018

            Best Exhaust System

            If you want that old school muscle car sound this the product for you notice a increase in performance from the beginning

            QuentinL

            Year: 2015 Submodel: GT

            Helpful (5)

          • 5/5

            Installation Time: Afternoon

            September 17, 2018

            Face Melters

            This exhaust produces rich, deliciously audible notes that will have you more worried about smiles per gallon as you gulp up apex after apex. Burble, check. Growl, check. Envious bystanders, check. You’ve seen the YouTube videos. You already know you’re buying it. Just do it already.

            Joe

            Year: 2017 Submodel: GT

            Helpful (8)

          • 5/5

            Installation Time: Afternoon

            August 16, 2018

            It sounds like freedom

            Picture George Washington singing the National Anthem while crossing the Delaware. Thats what it sounds like everytime you get on it. This exhaust is loud, in your face, and does not care about the people around you. Absolute must have for any mustang owner who loves to announce their presence. Side Note: There is a decent amount of drone cruising in 6th Gear at 2K. Its a trade off but I am more than happy to pay it to have my car sounding as amazing as it does.

            kiszler

            Year: 2015 Submodel: GT

            Helpful (8)

          • 5/5

            August 16, 2018

            Worth every penny!

            Full Review/Expereince with some tips. Shop install takes an hour and a half. From what they told me the fit was very well and they had no trouble with it (comes with instructions) and charged me $60. So if your shop tells you they’re having trouble they might not know what they’re doing. First start up after the install is extremely intense, you really get that aggressive sound you’re looking for so you should be extremely satisfied as the video doesn’t do the sound any justice, I was honestly shocked. People will definitely be breaking their necks trying to find the monster they hear driving down the road, it sounds that amazing! With that being said, the drone is absolutely killer, so don’t put this on something you’ll be driving every single day or you’ll regret. I drive my CS/GT around 10 miles a day on average. If you drive your GT over 40 miles/day you should really consider looking at something else because it feels like you’re in a commercial jet and will leave your head busting after a moderate drive. Avoid 100 mile drives at all costs! I’ll clear this up on a final note for those that live in an apartment or anywheres where you have a lot of neighbors. Expect complaints, yeah, seriously. I’m in an apartment while at college and the cold start blares so loud that I feel the need to hop in the car and get out of there as quickly as possible so break this in with your neighbors and tell them you’re not being this loud on purpose and hope they’re nice and understanding like mine because you’ll be heard within a 40-50 yard radius, no exaggeration. Summarized : If you’re worried about being too loud in your quiet neighborhood and take long daily drives, sorry to say but this won’t be for you, just a friendly warning. If not then this will be the best exhaust system you could ever have on your mustang!

            KJ

            Year: 2016 Submodel: GT

            Helpful (6)

          • 1/5

            Installation Time: Afternoon

            July 24, 2018

            Outlaw Catback

            Without going on a long rant, I’ll break it down nice and easy. The exhaust sounds amazing, high quality materials. The fitment is trash, I cut precisely as directed per the instructions and played endlessly with the exhaust and can not get the exhaust tips to line up for the life of me. I took it to multiple exhaust shops and they can not line the tips either, they stated kits are always like this. I would recommend just buying the mufflers and getting a custom exhaust built for better fitment than this kit.

            Daniel

            Year: 2017 Submodel: GT

            Helpful (8)

          • 5/5

            Installation Time: Afternoon

            July 06, 2018

            Great Exhaust

            I was looking for something that would be loud and unique and I found it. This was amazing its super loud but also sounds really amazing. Much better than the factory exhaust. It took some time to install because had forgotten that I needed to cut off some of the old pipe. Just make sure if you get this you are aware you won't be able to go back to the stock exhaust because you have to cut some of the pipe off.

            LawsonW

            Year: 2016 Submodel: GT

            Helpful (6)

          • 5/5

            Installation Time: Shop Install

            May 22, 2018

            Best sounding exhaust ever!

            had this system installed on my 727hp Roushcharged '17 GT. Everything I wanted in an exhaust system. Loud. Obnoxious. And when I drive to town everyone knows it. I didnt buy a supercharged Mustang to please anyone but me. And the way the outlaw catback makes my GT sound...is pure fun. I dont care what anyone tells you, This is the best bang for the buck exhaust out there.

            EARACHE

            Year: 2017 Submodel: GT

            Helpful (7)

          • 5/5

            Installation Time: Shop Install

            Installation Cost: $100-$250

            May 08, 2018

            The Outlaw

            I had the system installed at a local shop that a friend made me aware of and had it installed in my 2017 GT for $120.Designed for sprint cars it is on the loud side at higher RPM's.There is a slight drone at highway speeds but since installing them I've gotten MANY compliments on the sound of the exhaust.If your looking to wake up your GT this is a great mod !!

            ShawnL

            Year: 2017 Submodel: GT

            Helpful (6)

          • 5/5

            Installation Time: Afternoon

            April 23, 2018

            Absolute Beast

            I ordered my Flowmaster Outlaws on a Monday afternoon, they were delivered on Wednesday, and by Thursday afternoon my 2017 GT was turning heads. I couldn’t be more pleased. The sound is a deep growl and is better than I imagined.

            Mike

            Year: 2017 Submodel: GT

            Helpful (5)

          • 5/5

            Installation Time: Less than 1 Hour

            March 24, 2018

            Exhaust

            Louder than the video buy it turns heads and breaks necks at times.

            MarkD

            Year: 2016 Submodel: GT

            Helpful (5)

          • 5/5

            Installation Time: Shop Install

            Installation Cost: $100-$250

            March 13, 2018

            Amazing sound! The way the 5.0 should sound.

            This has a very nice aggressive sound very loud. Other reviews had some points in there about the drone, but honestly it’s not bad at all, barely noticeable. If you want to turn heads and have that nice distinct sound I suggest going with the outlaws. Definitely worth it. Shop install was in between 2-3 hours, wasn’t in any hurry that day anyways. $150 was the price.

            MambaDavid24

            Year: 2017 Submodel: GT

            Helpful (6)

          • 5/5

            Installation Time: Afternoon

            March 02, 2018

            RAW OUTLAW

            Me and a buddy installed these on my 17 GT S550 In about an hour and a half. Tips are a pain to get perfect. Other than that it was pretty basic. Definitely worth it! I originally was going to go with a different system...less aggressive. SO glad I didn't. I can honestly say I have not heard anything louder or better. I read up on multiple systems and am positive I made the right choice for me. I will say this, these are NOT for everyone. They are LOUD! The drone isn't as bad as others say...at least for me. However I can understand the claims. It all depends on the individual. I personally LOVE everything about it. Bottom line...if you want the nastiest sound around these are it. Go big or go home!

            MatH

            Year: 2017 Submodel: GT

            Helpful (6)

          • 5/5

            Installation Time: Less than 1 Hour

            January 31, 2018

            Flowmaster with Corsa Double X Pipe

            I have this Flowmaster connected with the Corsa Double X pipe and there’s no comparison to the Standard flowmaster set up. If you have this already, get The Corsa Double X pipe connected to it. So much better than this as is.

            CarmineB

            Year: 2017 Submodel: GT

            Helpful (6)

          • 1/5

            Installation Time: Shop Install

            Installation Cost: $100-$250

            December 29, 2017

            Ruined My Stang

            The review section for this product really let me down. I was looking for the deep muscle car sound of long ago, and I was sadly disappointed in this cat back system. Going from stock to this resulted in pressure inside the cabin around 2000 rpms that was incredibly painful to drive in. The drone is insane, much worse than other Flowmasters I have owned. BEWARE, there is no video that will describe the drone, as the low frequency will not come through accurately on any video. My brother commented that he felt as if he had been "punched in the earhole" after a short test drive. Not what you want happening to the passengers/drivers in the car. Do not put this system on a daily driver.....you have been warned. No noticeable throttle response improvement. This cat back system was professionally installed and then subsequently checked for a bad installation by a Ford service center. Uninstalled and sold on Craigslist for a loss after less than 50 miles. Don't ruin your new Mustang like I did. Stay away from this cat back system.

            JamesG

            Year: 2017 Submodel: GT

            Helpful (10)

          • 5/5

            Installation Time: Less than 1 Hour

            December 01, 2017

            Holy drone Batman!!!

            This exhaust, hands-down, has completely transformed my cars attitude!! I absolutely love it!!! The drone is pretty intense but I personally don't mind. Everyone that hears my exhaust, even other Mustang owners, are asking me what it is because it sounds fantastic!!! Most of the drone is easily fixable with some Dynamat.

            Joe

            Year: 2017 Submodel: GT

            Helpful (5)

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