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

Market Price $1,095.99 You Save 13% ($143.02)
Our Price

$952.97

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  • Item 387145
  • MPN# 817734

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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

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?
  • GT - 15, 16, 17

Not compatible with Convertibles due to different bracing

People Who Bought This Item Also Bought

Most Helpful Reviews

5/5
Not only loud but perfect tone

I spent months looking at different cat back systems, listening to different sound clips and asking friends with experience about different exhaust. I was drawn towards the outlaw catback system based ...

Read More
Helpful (3)

5/5
Love the sound

I love this exhaust. I had axle back American thunders on my 2011 gt and thought they sounded great, for my 2015 I wanted something mean. The xpipe part didn't fit up perfect and needed a second cut, the ...

Read More
Helpful (3)

Overall Rating 4.9 out of 5 stars
Read All 30 Reviews

Customer Photos (7) Submit Your Photo

View All 7 Photos

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12 Questions / 6 Answers

Ask a Question

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 ?

JaiA

  • 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.

    KevinD92

Helpful (1)

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?

JaewonL

  • This Flowmaster Outlaw Cat-Back Exhaust is designed for the GT's only, however, if your shop is cutting and welding this unit, it can be made to fit.

    AMJEFF

Helpful (0)

any horse power gain from a 3in cat back

peppersam

  • Hello, increasing the diameter of the exhaust and freeing it up to flow better will provide a boost in power. These coyotes like to breath so all the better to open them up a bit.

    Ryan H

Helpful (0)

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.

Anonymous

  • Some is some cutting required to your factory exhaust but do not worry as Flowmaster has instructions that come with this exhaust that will guide you to the proper cut and install.

    KevinD92

Helpful (0)

Will this fit on a European spec GT Fastback, the right hand drive model?

Anonymous

  • This is only confirmed to fit on Euro spec GT fastbacks. As long as the underbody is the same as the US spec Mustangs, this may be compatible. Please contact your local Ford dealer for further information.

    KevinD92

Helpful (0)

Can this exhaust fit with long tube headers and if so what headers will fit this?

Anonymous

  • This exhaust is to be used with stock or aftermarket shorty headers.

    KevinD92

Helpful (0)

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Customer Reviews (30) Write a Review

Overall Rating 4.9

out of 5 stars

Installation Time:Afternoon

Installation Cost:$100-$250

  • Loudness / Volume 5 5
  • Exhaust Note 4.857143 4.9
  • Fit & Finish 4.785714 4.8
  • Bang For Your Buck 4.928571 4.9



  • 5/5

    Installation Time: Afternoon

    January 13, 2017

    Not only loud but perfect tone

    I spent months looking at different cat back systems, listening to different sound clips and asking friends with experience about different exhaust. I was drawn towards the outlaw catback system based off price, but having the crisp sound of an x pipe while still being very throaty. Let me tell you...THIS THING IS LOUD. This wakes up the 5.0 like you can't believe. Love the tone. Drone is nasty at lower rpms but I do currently have the sound tube still hooked up. Installation is very easy. Cutting the exhaust is tight but simple enough. The rest is easy this does not take very long. All in all, best bang for your buck this system competes with the top brands by far. Very happy with this purchase and thank you American muscle for the insightful videos

    JOEBYYYY

    Year: 2016 Submodel: GT

    Helpful (3)

  • 5/5

    Installation Time: Afternoon

    October 17, 2015

    Love the sound

    I love this exhaust. I had axle back American thunders on my 2011 gt and thought they sounded great, for my 2015 I wanted something mean. The xpipe part didn't fit up perfect and needed a second cut, the install took a little over an hr for a shop to do and was 100$. If you don't like loud, low deep sound into screaming raspy race like exhaust note don't buy this, in fact don't buy the 5.0 jk, but seriously. The video doesn't do it justice, it's loud, very loud and mean, I couldn't be happier.

    CaptainAmerica

    Year: 2015 Submodel: GT Newport News VA

    Helpful (3)

  • 5/5

    Installation Time: Shop Install

    Installation Cost: $100-$250

    February 04, 2017

    Awesome

    Came fast as normal and had a local shop install for about 150 with no fitment problems. And fyi didn't need o2 extensions. This exhaust is sooo loud. Puts a smile on my face every time. Like others said the clip doesn't do this justice. It's loud and thunderous.

    Skovac2

    Year: 2015 Submodel: GT

    Helpful (2)

  • 5/5

    July 14, 2016

    Perfect levels of sound

    This exhaust is amazing at all RPM. Below 2000 it is louder than stock but only as a low rumble. Above 3000 it roars and at top end it screams. Perfect for cruising a neighborhood or blazing down a highway. It is annoyingly drone at around 2000 but nothing you can't get over for how great it sounds otherwise.

    Bailes

    Year: 2016 Submodel: GT

    Helpful (2)

  • 5/5

    Installation Time: Less than 1 Hour

    April 29, 2016

    Amazing exhaust

    I hated the stock sound, this exhaust is loud! Don't buy if you don't like a lot of noise. But it's wonderful sounds so good!

    Colyn

    Year: 2016 Submodel: GT

    Helpful (2)

  • 5/5

    Installation Time: Less than 1 Hour

    November 05, 2015

    This one is a L.... but after install 2 sherry bomb's PERFECT !!

    This one is a L.... but after installing 2 sherry bomb's PERFECT !! and we will w.... up our neighbors.... at 5am

    Kiwi2015GT

    Year: 2015 Submodel: GT Florida

    Helpful (2)

  • 4/5

    Installation Time: Less than 1 Hour

    October 17, 2017

    WOW

    I recommend doing the custom catback, Buy the Scavenger Series X-pipe and then the Axelback Outlaw, its all direct bolt on so no need to cut.. I had the Outlaw on my 2015 GT supercharged, and It was VERY LOUD. No youtube video will justify the sound you need to hear it in person. So overall.. great price and amazing sound. Now for the bad... THE DRONE IS SO BAD! about 2k there is no way to have a conversation without yelling. Really gets a bit too much. if you wanna wake the neighborhood and turn heads when you drive.. get the outlaw.

    Shy

    Year: 2015 Submodel: GT

    Helpful (1)

  • 5/5

    Installation Time: Afternoon

    July 27, 2017

    awesome sound

    This was a great purchase for the money, the sound is awesome. Everyone that hears it loves it.

    MustangMike

    Year: 2017 Submodel: GT

    Helpful (1)

  • 5/5

    Installation Time: Less than 1 Hour

    June 29, 2017

    Refined tone, but still loud

    This was a spectacular purchase as the previous owner of my 2015 Musang GT Premium PP had done a muffler and resonator delete which was god awful loudness from the exhaust. The Flowmaster American-Outlaw cat-back system refined that noise but still lets me make some noise.

    804rvaBEST

    Year: 2015 Submodel: GT

    Helpful (1)

  • 5/5

    Installation Time: Afternoon

    June 15, 2017

    Incredible Sound

    If you're looking for a well made exhaust that is cheaper than others and is loud, I mean REALLY loud, this one is the one to buy. Small modification to the factory pipes is needed (cut about 11 inches out from the cats) but other than that, the fit is superb. There is some drone in the 2k RPM range, but the sound this exhaust produces is one of the best, especially in the 4500 - 6500 RPM range. Would recommend to anyone looking for an aftermarket exhaust for their S550.

    Greg

    Year: 2015 Submodel: GT

    Helpful (1)

  • 5/5

    April 25, 2017

    Loud roar #V8Beast

    This exhaust is loud, if you don't mind announcing your presence everywhere and having to hear some humming every no and then in the cabin then go for it. It's super load and there's nothing quite about the Outlaw. If you plan on driving you Stang daily and can't stang the roar then go with something quieter, SERIOSLY. I am single and don't use my Stang daily so it's fine but it can and probably get on your nerves since now a days we are used to quite cabins. You will have to sacrifice commodity for Thunder lol. A great exhaust to unleash the V8 beast.

    JuanR

    Year: 2016 Submodel: GT

    Helpful (1)

  • 5/5

    Installation Time: Afternoon

    March 27, 2017

    WOW!!!! ITS LOUD!!!!

    This was not my first choice but I'm glad I went with it. If you are looking for a loud attention getter this is your exhaust. The only thing I didn't like was having to use a set of clamps that came with the stock exhaust. Install was very simple with jack stands in my garage. I'm very pleased with the look, sound and quality of Flowmaster and would highly encourage anyone looking for an aftermarket exhaust to look at this budget friendly system...

    FelipeS

    Year: 2017 Submodel: GT

    Helpful (1)

  • 5/5

    Installation Time: Shop Install

    Installation Cost: $100-$250

    February 27, 2017

    Awesome sound

    I combined BBK longtube headers and this Flowmaster Catback and it honestly is what a mustang is supposed to sound like. Strong and deep sound, very happy with the purchase. Once I ordered it, it arrived very quickly and was not hard to install.

    birdman

    Year: 2015 Submodel: GT

    Helpful (1)

  • 5/5

    Installation Time: Less than 1 Hour

    December 06, 2016

    Beastly sound

    The video doesn't do this exhaust any justice. This exhaust is LOUD and I mean LOUD! It has that nice deep growl flow master is known for. Non- of that back firing sound a lot of exhaust have. Gives it that true American muscle car sound. The drone isn't bad at all around 2rpm, just an amazing exhaust highly recommended. Very fair price for what you get. Warning though! If your not farmillar with an exhaust like this, I'd recommend finding some place to check out the sound in person before you order. May be too much for some people. I absolutely love it, and perfect combo with the new KandN cold air intake I installed with it.

    Blueskys72

    Year: 2016 Submodel: GT

    Helpful (1)

  • 5/5

    August 26, 2016

    Sweet sounding growl

    Purchased the Race Ramps and installed these LOUD and awesome OUTLAWS in about 3 hours. I was a little hesitant about cutting the factory pipes but it was well worth it. I took it for a run and man did the Heads turn..... Fantastic sound if you want deep tone and pop, pop....pop,pop....and crumble, crumble, crumble.. I am glad I listened to all audio clips and chose this one! Well Worth the Price and install time.

    LocoPony

    Year: 2016 Submodel: GT

    Helpful (1)

  • 5/5

    Installation Time: Shop Install

    Installation Cost: 0-$100

    April 26, 2016

    Flow master outlaw is mean

    My car is now the loudest car on the road, and the price was unbeatable. It has the aggressive sound you want and will blow your eardrums out. Everyone I have shown has been in awe from my grandma to other mustang enthusiasts.

    Jfrazin

    Year: 2015 Submodel: GT

    Helpful (1)

  • 5/5

    Installation Time: Shop Install

    Installation Cost: 0-$100

    October 09, 2015

    Sounds absolutely amazing

    If you are looking for a loud exhaust, that's definitely what this will do for you. I was able to drive another mustang that had this system installed already before I chose to pick this. I really like the sound of it a lot! It's loud but the drone really isn't bad at all. When I open it up it's like music to my ears. Honestly, compared to other systems that reach over $1000, this is definitely a lot better value. You HAVE to like a loud system though. I'm absolutely satisfied and definitely recommend it and hope this review will help you make your decision a little easier.

    jfame

    Year: 2015 Submodel: GT Orangeville, PA

    Helpful (1)

  • 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 (0)

  • 5/5

    Installation Time: Afternoon

    November 02, 2017

    Amazing

    Took these to a local shop and they installed them, took maybe 3 hours total. This exhaust is extremely LOUD! I never expected how much of a difference these could make. Don't buy these if you don't want to wake up your entire neighborhood!

    Brian

    Year: 2017 Submodel: GT

    Helpful (0)

  • 5/5

    Installation Time: Afternoon

    October 30, 2017

    I love it !!!

    Great sound it is loud but just right it may seem like fuel economy is worse but its really you that you always want to hear so you rev it higher it was easy to install going to need a helping hand but took me about 3 hours worth the money !

    JoeyM

    Year: 2016 Submodel: GT

    Helpful (0)

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