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Flowmaster American Thunder Axle-Back Exhaust (15-17 GT)

Market Price $693.99 You Save 13% ($91.02)
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$602.97

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  • Item 384452
  • MPN# 817749

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    Features, Videos & Details

    • Aggressive Flowmaster Super 44 Series Sound
    • Durable 409 Stainless Steel Construction
    • 2.5" Mandrel-Bent Tubing
    • 4" Polished 304 Stainless Steel Tips
    • Includes (2) Flowmaster Super 44 Series Mufflers
    • Compatible with Fastback and Convertible
    • Fits All 2015-2017 GT Mustangs

    Review & Installation Video

    Hey, everybody. Justin with AmericanMuscle.com here, taking a quick look at the American Thunder Axle-Back from Flowmaster fitting your 2015 Ford Mustang GT. Flowmaster is, without a doubt, one of the most recognizable names in the Mustang world, and it has been the hot rodders' choice for many decades. Now, we've used several of their products in some of our past builds, including the recent BAMA Terminator. If you guys haven't seen these builds yet, what are you waiting for? Be sure to check out some of our project car builds in addition to the best Mustang specific content on the web by checking out our YouTube Channel, American Muscle videos. So the American Thunder from Flowmaster is one of those tried and true systems that sounds killer on just about every generation Mustang, including the new 2015 Coyote powered Ford Mustang GT. Now, that iconic sound comes courtesy of the Super 44 Series mufflers here which will give your S550 just a little bit more bark, but won't wake the neighbors in the process. The entire system has been constructed from durable 409 grade stainless steel and features this durable high-temp black coating here, which should help reduce any corrosion over the years. Piping is all 2-1/2 inch mandrel bent, and we're looking at 4-inch slash cut tips embossed with that iconic Flowmaster logo. Now, guys, if I haven't answered every single one of your questions about the American Thunder here and you'd like to see more detailed information along with some detailed install tips, then be sure to check out the product page at AmericanMuscle.com if you haven't already done so. As you may or may not have heard by now, installing an Axle-Back onto your 2015 Mustang will require some cutting, as is the case here with the Flowmaster American Thunder. But don't worry. As long as you take your time, follow the detailed instructions, you should have no problems knocking it out in about an hour from start to finish. Either way, guys, if you do have any more questions about the exhaust or about the actual install, feel free to reach out to one of our Mustang experts any time using the 1-800 number. They're always standing by, ready to help a fellow Mustang owner in need. Now, it's time to hear how the Flowmaster American Thunder Axle-Back sounds compared to the factory exhaust.

    Classic Flowmaster Sound. Add the unmistakable Flowmaster sound to your S550 GT with an American Thunder Series Axle-Back Exhaust System from AmericanMuscle. This axle-back system improves exhaust flow using Flowmaster's Super 44 Series mufflers for that classic aggressive muscle car exhaust note your high powered Pony deserves.

    Stainless Steel Construction. Constructed from durable 2.5" 16 gauge 409 stainless steel tubing for it's corrosion resistant properties, the Flowmaster American Thunder Axle-Back features Super 44 Series mufflers with massive 4.0" diameter polished 304 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.

    Cut & Clamp Installation. The installation of this Axle-Back Exhaust requires cutting and removing the factory muffler assemblies and clamping the new muffler assemblies in place. Clamps and instructions are provided.

    Application. This Flowmaster American Thunder Series Axle-Back Exhaust System is designed to fit the 2015-2017 GT Mustangs, including fastback and convertible models.

    Fitment: 2015 2016 2017 Details

    What's in the Box
    • (2) Muffler assemblies
    Installation Info
    Tech Specs
    Axle-Back Exhaust Specifications
    Piping Material: 409 Stainless Steel Tip Material : Polished 304 Stainless Steel
    Piping Size: 2.5" Tip Size: 4"
    Muffler Type: Chambered Fitment: 2015-2017 GT
    Will it fit my Mustang?
    • GT - 15, 16, 17

    Most Helpful Reviews

    5/5
    Thunder and Lightning

    I purchased the flowmaster american thunder axleback along with the flowmaster x pipe and my car finally sounds like a real muscle car you will definitely turn heads with this combo please don't purchase ...

    Read More
    Helpful (4)

    5/5
    The Mustang GT exhaust system

    Flowmaster has been on every Mustang GT I have owned. Two 1987 GTs , 1991 LX 5.0, 1993 GT, 2003 GT, 2006 GT, 2007 GT, 2010 GT and the 2017 GT The only exhaust for the GT Mustang. Dont be a Hipster ...

    Read More
    Helpful (3)

    Overall Rating 4.5 out of 5 stars
    Read All 39 Reviews

    Customer Photos (9) Submit Your Photo

    View All 9 Photos

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    5 Questions / 5 Answers

    Ask a Question

    I already did a flowmaster resonator delete x pipe still running the stock mufflers. Will this system bolt up to that without further cutting?

    BokodiF

    • The installation of Flowmaster American Thunder Axle-Back Exhaust would require cutting and removing the factory mufflers and clamping the new mufflers in place.

      Pat K

    Helpful (1)

    Will this axleback be a direct bolt-on to the boss 302 style mid pipe?

    DerrickC

    • The Flowmaster American Thunder Axle-Back Exhaust will be a direct bolt on when using the Boss 302 style mid pipe.

      Rob D

    Helpful (0)

    Will this exhaust fit a GT Convertible?

    GabrielB

    • This Flowmaster American Thunder Axle-Back Exhaust is compatible with the Fastback or Convertible 15-17 Mustang GT.

      AMKody

    Helpful (0)

    My current 2015 Mustang GT already has a Catback Flowmaster Exhaust system on it . I just bought this car, even though I am not crazy about how loud it is. The previous owner of the car had the resonator removed AND had a cold air filter system added on it. I think that the current FM mufflers on it are not sufficient enough to handle the additional air flow and power. Can these replace the ones that are there now and will calm the beast some? Thanks for your time.

    12345678910

    • The Flowmaster American Thunder Axle-Back Exhaust will be a quieter more tame option, especially compared to that of the outlaws. However the mufflers are only there to quit or change the sound and do not effect the airflow as they are too far down the system.

      AM MikeW

    Helpful (0)

    Will this be able to be run in-line with my Ford Racing X-Pipe? Or will it require a shop custom fab this on? I'm afraid that the use of four clamps from the X-Pipe to the mufflers will make the exhaust unstable.

    David

    • The X-pipe if going to be mounted further up from where the Axle-Back Exhaust would be attaching to. Your X-Pipe should have no affect on installing the Flowmaster American Thunder Axle-Back Exhaust (15-17 GT).

      SalC7

    Helpful (0)

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    Customer Reviews (39) Write a Review

    Overall Rating 4.5

    out of 5 stars

    Installation Time:Afternoon

    Installation Cost:$100-$250

    • Loudness / Volume 4.057143 4.1
    • Exhaust Note 4.657143 4.7
    • Fit & Finish 4.571429 4.6
    • Bang For Your Buck 4.6 4.6



    • 5/5

      August 02, 2016

      Thunder and Lightning

      I purchased the flowmaster american thunder axleback along with the flowmaster x pipe and my car finally sounds like a real muscle car you will definitely turn heads with this combo please don't purchase the axleback and team it with the old resonator won't sound the same trust me.

      Chitown

      Year: 2016 Submodel: GT

      Helpful (4)

    • 3/5

      Installation Time: Shop Install

      Installation Cost: 0-$100

      May 14, 2017

      Too much drone

      Bought them and installed on a Tuesday. Immediately noticed the low unwanted rpm drone. Took them off and sold them the next Friday. Just couldn't stand thw continuous drone inside the cabin. Also as the diameter of the pipe is bigger thus ending on the exhaust tip not centering.

      Caballoballo

      Year: 2015 Submodel: GT

      Helpful (3)

    • 2/5

      Installation Time: Less than 1 Hour

      April 13, 2017

      Flub Masters

      Very disappointed in product. One muffler had back side not even painted fully. The drone is really bad also . Around 1300rpm you cant even hear the radio.You think they would have solved that problem by now. Had them on my 2006 GT . The quality was much better back then with no drone at all. Im done with Flowmaster.

      JohnS

      Year: 2017 Submodel: GT

      Helpful (3)

    • 5/5

      Installation Time: Afternoon

      November 22, 2016

      The Mustang GT exhaust system

      Flowmaster has been on every Mustang GT I have owned. Two 1987 GTs , 1991 LX 5.0, 1993 GT, 2003 GT, 2006 GT, 2007 GT, 2010 GT and the 2017 GT The only exhaust for the GT Mustang. Dont be a Hipster and use anything else

      Gadget

      Year: 2017 Submodel: GT

      Helpful (3)

    • 5/5

      September 10, 2016

      2016 Black-mobile

      Bolt on to my likings with a 2 inch cut instead of 2 1/2 inch. The latter would cause the tips to stick out further than I'd like. Looks and sound great.

      Agent

      Year: 2016 Submodel: GT

      Helpful (3)

    • 5/5

      August 22, 2016

      Awesome Sound

      I bought this with the Flowmater Scavenger X-pipe. The sound is amazing. Thumps up everywhere I go.

      BoostStang

      Year: 2016 Submodel: GT

      Helpful (3)

    • 5/5

      July 15, 2016

      Exactly how a Mustang should sound

      I was not sure if swapping out the exhaust would be worth the money but boy I'm glad I did. The Flowmaster is definitely worth it. The note is deep and just a bit louder than stock. Great build quality too.

      Daver90s

      Year: 2016 Submodel: GT

      Helpful (3)

    • 3/5

      Installation Time: Shop Install

      Installation Cost: 0-$100

      June 13, 2016

      American Thunder not a perfect fit

      The exhaust hangers did not line up with the hangers, so the installer had to cut the hangers and weld them on to the pipe in order to get the fitment correctly. I'm very disappointed with flowmasters quality control. Apparently they did not inspect this particular system or someone did not do their job and I got stuck with a poorly constructed system. Otherwise, its ok I won't purchase flowmaster again I feel I should have been able to send it back to the mfg. to get it replaced.

      forgiven1

      Year: 2015 Submodel: GT

      Helpful (3)

    • 5/5

      Installation Time: Afternoon

      June 09, 2016

      Great sound

      Fit great although recommend welding instead but clamps work fine. Sound good, not to loud and not to quiet with minimum drone.

      nate68

      Year: 2016 Submodel: GT

      Helpful (3)

    • 5/5

      Installation Time: Afternoon

      September 13, 2017

      Flowmaster is the only way to go

      Had mustangs for years. Flowmaster has been on every one of them. If you're struggling to decide, let this review help you. Super 44's give the mustang its real muscle car sound. Sounds clips don't do justice, it catches everyone's ear while driving. The sound is not obnoxious, it's clean and mean. Like a stang should sound. Combo this specific pack with and h or x pipe, an h or x style resignator delete and you won't be sorry! Install was easy, sound and flow are true. IMO the 44 series wake the car up. As you add more modes, it unleashes more!!

      RalphC

      Year: 2017 Submodel: GT

      Helpful (2)

    • 3/5

      Installation Time: Shop Install

      June 19, 2017

      Drone

      Too much drone. But way better than the Roush. The drone is pretty bad with the "H-Pipe". The Roush with the "H-Pipe" sounded horrible. It sounds nice outside the car...low rumble sound compared to the raspy, tinny sound of the Roush.

      Jimbo2738

      Year: 2016 Submodel: GT

      Helpful (2)

    • 4/5

      Installation Time: Less than 1 Hour

      June 09, 2017

      Good sound

      These sound great. I did not want anything too loud. However there was a bit of drone in the car but I believe that removing the resinator on the car caused this. There is an oddo from the coating buring off for a few weeks.

      RyanR

      Year: 2016 Submodel: GT

      Helpful (2)

    • 4/5

      Installation Time: Shop Install

      Installation Cost: $100-$250

      March 23, 2017

      Issues with clamp mounting

      Went to Meineke Muffler to get this axle-back exhaust installed on my 2015 Mustang GT. The Flowmaster pipe did not slip onto the Ford pipe at all. I looked at it myself and measured the diameters to verify the dilemma. Either the Flowmaster pipe diameter is too small or the Ford pipe diameter is too big. Hard to tell who has the manufacturing variation. All the technician could at that point was modify the tube length and butt weld the Flowmasters tubes to the to the Ford tubes. Installation cost went up accordingly.

      Volker

      Year: 2015 Submodel: GT

      Helpful (2)

    • 5/5

      Installation Time: Less than 1 Hour

      October 04, 2016

      Perfect

      American Thunder makes my 16 Mustang GT sound like a muscle car straight from 1969! Love the sound. Not to loud but not too soft. Perfect

      Harry

      Year: 2016 Submodel: GT

      Helpful (2)

    • 5/5

      Installation Time: Afternoon

      September 26, 2016

      GT

      A lot better sound to the car. Love the flowmaster exhaust. Wasn't too hard to install either. Looking forward to more purchases with you guys.

      Brent

      Year: 2015 Submodel: GT

      Helpful (2)

    • 5/5

      Installation Time: Less than 1 Hour

      July 01, 2016

      Perfect sound and not too loud

      This axle back kit is worth every penny. Sounds great and doesn't cackle. This is a mature sounding exhaust that will give you just a bit more 'throat' to your car. Take your time and measure twice before cutting, the install is very easy. NOTE: Do yourself a favor and go to an auto parts store and spend $4 on two good 2.5" clamps. The ones that come with the system are horrible and will snap if you tighten too much.

      Hanric

      Year: 2015 Submodel: GT

      Helpful (2)

    • 5/5

      Installation Time: Less than 1 Hour

      May 27, 2016

      Gave me a halfie

      From a purr to a growl. Couldn't be happier. I wanted the 90's mustang fox-body sound. I got it. Ground rumbles but it's not too overbearing. Great value for the price.

      Baddogg5150

      Year: 2016 Submodel: GT

      Helpful (2)

    • 5/5

      Installation Time: Less than 1 Hour

      August 25, 2015

      Consistent quality and great sound for the money

      This is the second Mustang GT that I've purchased the Flowmaster American Thunder axle-back exhaust for and I've couldn't be happier with the fit, finish, and the overall quality of the product. The sound is exactly what i was looking for and there is minimal drone.

      TripleYellowGT

      Year: 2015 Submodel: GT Ankeny, IA

      Helpful (2)

    • 5/5

      Installation Time: Less than 1 Hour

      August 21, 2015

      Just the sound i wanted

      I was a little nervous on adding this. The car is only two months old and cutting the exhaust and possibly not the sound i wanted. But, after cutting and installing which went great and easy, But firing it up and hearing it was pleased. Than the test drive, perfect. I am very happy. TY American Muscle, satisfied me again.

      nascman1

      Year: 2015 Submodel: GT Easton pa.

      Helpful (2)

    • 5/5

      Installation Time: Shop Install

      Installation Cost: 0-$100

      December 11, 2015

      Brings the Mustang GT to life

      I've had Flowmasters on my '92 LX 5.0, 2002 GT, and now, my '15 GT. My 2015 has the axle back system which gives your Mustang GT the proper sound with the exhaust burble during downshifts, the cruising rumble, and the powerful roar during upshifts. All of this without intrusive resonance, or vibration. If you want an alternative to the Ford stock exhaust, this is the one.

      Wayne

      Year: 2015 Submodel: GT Myrtle Beach, SC

      Helpful (1)

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