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Flowmaster American Thunder Cat-Back Exhaust (15-17 GT Fastback)

AmericanMuscle no longer carries the Flowmaster American Thunder Cat-Back Exhaust (15-17 GT Fastback). Please check out 2015-2019 Mustang Cat-Back Exhaust for an updated selection.

Features, Video & Details

  • Aggressive Flowmaster 60 Series Sound
  • Durable 409 Stainless Steel Construction
  • 3" Mandrel-Bent Tubing
  • 4" Polished 304 Stainless Steel Tips
  • Includes Two Flowmaster 60 Series Mufflers
  • Fits 2015-2017 GT Fastback Mustangs

Review & Installation Video

Review & Install Video

Justin: Hey everyone, I'm Justin with americanmuscle.com and this is my quick look at the Flowmaster American Thunder Series Catback Exhaust System fitting your 2015 Mustang GT. Flowmaster's without a doubt one of the most recognizable names in the Mustang world or the muscle car world in general. In fact, we use several Flowmaster systems on some of our own project cars here at americanmuscle.com, including the Bama Terminator and also Project Coyote. All right, for all my Flowmaster fans out there you can expect that signature iconic Flowmaster sound from the American Thunder Series Catback here, thanks largely in part to the Super 44 Delta Series mufflers that are pretty much responsible for defining the Flowmaster brand through sound. Now, this system isn't going to be as loud as The Outlaw Series System for instance, but since it is a Catback and since you are deleting that suitcase factory resonator, you can expect a nice aggressive deep tone. In fact, Flowmaster says that the Super 44 Delta Series muffler is the deepest sounding highest performing two chamber muffler they've produced to date. The system consists of a durable 409 grade stainless steel for the construction while the Super 44 Series mufflers here have been coated with a black high temperature coating, a Flowmaster trademark to help resist any corrosion over the years. All the piping is all two and a half inch mandrel vent. On the tips themselves are four inch slash cut embossed with that iconic Flowmaster logo. Now, this would be a great time to tell you guys that the product page contains a ton of useful information such as customer reviews, detailed product specifics, and of course a detailed walk-through install guide. So if you're not already watching this on our product page, be sure to head back and click the link below. Speaking of that install, guys, I do want to tell you that the Flowmaster American Thunder Series Catback System is one of the few systems that you will have to cut to get installed. Now, with that in mind just make sure that you have all the right tools on hand, including a sawzall or something similar, along with a fresh metal blade and about two hours of your time to get everything bolted up. Again, if you have any questions whatsoever, you can always reach out to our team of Mustang experts by phone or email. They're always standing by ready to help a fellow Mustang owner in their time of need. Now, let's hear how the Flowmaster American Thunder Series Catback sounds compared to our factory exhaust.

Classic Flowmaster Sound. Add the unmistakable Flowmaster sound to your Fastback S550 Mustang GT with an American Thunder Series Cat-Back Exhaust System from AmericanMuscle. This catback system improves exhaust flow using Flowmaster's 60 Series mufflers for that classic aggressive muscle car exhaust note your high powered Pony deserves.

Stainless Steel Construction. Constructed from durable 3" 16 gauge 409 stainless steel tubing for it's corrosion resistant properties, the Flowmaster American Thunder Cat-Back features 60 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.

Application. This Flowmaster American Thunder Series Cat-Back exhaust system is designed to fit the 2015-2017 GT Fastback Mustangs for both great looks and great sound. Not compatible with convertibles. Reuses the stock clamps for installation.

Fitment: 2015 2016 2017 Details

MPN# 817730

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

What's in the Box
  • (2) Muffler assemblies
  • (2) Pipes
Installation Info
Tech Specs
Cat-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 Fastback
Will it fit my Mustang?

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      Questions & Answers (7)

      5 Top Rated Questions

      Can i use this set up with the BBK 1-3/4 in. Ceramic Long Tube Headers?

      • The Flowmaster American Thunder Cat-Back Exhaust will not properly pair up with your Mustang due to the extended length of the headers. You would need to cut and modify the Flowmaster system for it to properly pair with your long tube headers.

      Helpful (2)

      Do I need a tune with this exhaust system

      • This exhaust does not require a tune.

      Helpful (1)

      What muffler comes with this kit? The description says it’s a 60 series and the videos says it’s a super 44. I have a super 40 on my 2015 f150 and love the sound, was for the same for my Mustang

      • The Flowmaster American Thunder Cat-Back Exhaust utilizes Two Flowmaster60 Series Mufflers.

      Helpful (1)

      What would the expected horse power gains be with the exhaust ?

      • The gains would be between 10-15 HP.

      Helpful (1)

      does this system drone at speed

      • The Flowmaster system will have some drone to them yes.

      Helpful (1)
      Post Your Question
      2 More Questions
      does this have an x or h pipe 1 answer
      Hi, is this product 50-state street legal 1 answer

        Customer Reviews (14) Write a Review

        Overall Rating 4.8

        out of 5 stars

        Installation Time:Full Day

        Installation Cost:$100-$250

        • Loudness / Volume 4.214286 4.2
        • Exhaust Note 4.857143 4.9
        • Fit & Finish 4.428571 4.4
        • Bang For Your Buck 4.642857 4.6



        • 5/5

          Installation Time: Less than 1 Hour

          July 03, 2018

          It has found it voice

          My 2017 GT reminded me of Mike Tyson, it had all the power and endurance you could want but when it spoke, you couldn't help but chuckle a bit. This exhaust gives the GT the voice it should have had all along. Start up and Idle are those fat and deep notes I wanted from a old school muscle car. Step on the gas and it sounds off proudly. Cruising highway speeds are drone free and not bad at all. Can't really go wrong with this package. I had a local muffler shop install it in an hour for less than $200.

          JarrodP

          Year: 2017 Submodel: GT

          Helpful (8)

        • 4/5

          Installation Time: Shop Install

          Installation Cost: $100-$250

          April 11, 2018

          2015 Mustang GT American Thunder

          I am extremely pleased with this catback system. I love the sound, kinda wish it was slightly a deeper sound but overall I am happy with this purchase and would recommend it to others.

          JosephO

          Year: 2015 Submodel: GT

          Helpful (6)

        • 5/5

          Installation Time: Shop Install

          Installation Cost: $100-$250

          October 10, 2017

          American Thunder Cat Back

          I got my American Thunder cat back in 2015 I did not do a review doing one now I paid $989.00 for mine in 2015 I was sent 3" pipe and 40 series delta mufflers it was all new in box I was happy with the 3" and the 40 series the sound is still awesome now I have headers with no cats still sounds awesome keep up the good work Flowmaster and American Muscle

          feardark69

          Year: 2015 Submodel: GT

          Helpful (7)

        • 5/5

          Installation Time: Shop Install

          Installation Cost: 0-$100

          October 05, 2017

          2016 Mustang GT American thunder fatback exhaust

          This is what I needed to make my Mustang Sound like a Mustang with bite. I love the tone. It’s not too loud at idle but sounds off When you accelerate. Install was easy. Fit was perfect.

          DouglasM

          Year: 2016 Submodel: GT

          Helpful (6)

        • 5/5

          Installation Time: Afternoon

          September 14, 2017

          Satisfied

          Cam quick unharmed happy with it, it fit on just right had no problems with the product

          RicardoR

          Year: 2016 Submodel: GT

          Helpful (6)

        • 5/5

          Installation Time: Shop Install

          Installation Cost: $100-$250

          July 03, 2017

          Sounds great!

          It sounds perfect. Not annoying to ride with, but a nice deep sound.

          Jaret

          Year: 2017 Submodel: GT

          Helpful (6)

        • 5/5

          Installation Time: Shop Install

          Installation Cost: 0-$100

          May 26, 2017

          American Thunder For Memorial Day

          Just exactly what I wanted. Nice deep rumble, no rasp and a few HP

          JohnR

          Year: 2015 Submodel: GT

          Helpful (7)

        • 5/5

          Installation Time: Afternoon

          May 23, 2017

          American thunder cat

          The sound is awesome! Feels more responsive, deep tone through every gear. And easy installation 2 hrs

          TimothyC

          Year: 2017 Submodel: GT

          Helpful (8)

        • 5/5

          Installation Time: Afternoon

          January 25, 2016

          The amazing flowmaster sound and performance

          Flowmaster always was one of my top choices in exhaust when I have owned a mustang. Classic sound and great performance. Installation took a little time but it was worth the work. Very satisfied! Great job American Muscle.

          Charles

          Year: 2015 Submodel: GT New Orleans, LA

          Helpful (8)

        • 5/5

          Installation Time: Less than 1 Hour

          October 19, 2015

          GREAT EXHAUST!!

          This is a great way to open up your 2015 Mustang GT's exhaust. Very happy with the ease of installation. I would have given 5 starts on Fit and Finish, but it seems to be off to the right a bit. Tried numerous adjustments and can't seem to get it centered. Not horribly noticeable, but nevertheless off. It is going to take a little bit of bending of the hangers to get it right, but it will accomplish this when I install the Headers and weld it all together. Otherwise, if sound and quality is what you desire, then look no further!! Flowmaster is still the one when it comes to making your Stang a "STANG."

          StuCazz

          Year: 2015 Submodel: GT Mount Dora, Fl

          Helpful (9)

        • 5/5

          Installation Time: Shop Install

          September 04, 2015

          Solid value and fun to drive

          I originally purchased the Flowmaster catback Outlaw series for my new 2015 GT pony. While amazingly deep and throaty it was also amazingly loud with a resonance between 1900 and 2100 rpms that made stereo listening or talking in the passenger compartment impossible. I replaced it with the Flowmaster American Thunder series and found exactly what I needed for pure driving pleasure. This series is still deep the throaty (although not so much as the Outlaw series) but has just amount of volume and 'thunder' to turn heads and make people wish they were driving the 'pony' instead of you. When you kick the gas pedal a little you really hear the pipes roar. I would recommend this series for anyone looking for daily driving fun with enough roar to turn heads in envy.

          Skip

          Year: 2015 Submodel: GT Harrisburg PA

          Helpful (12)

        • 3/5

          Installation Time: Weekend

          August 03, 2015

          Used system

          I received a used exhaust system from American Muscle for a new price. Nothing was done by American Muscle to fix the problem. I would recommend buying this system else where.

          1UnnsatisfiedCustomer

          Year: 2015 Submodel: GT Belton,Tx

          Helpful (10)

        • 5/5

          Installation Time: Less than 1 Hour

          May 29, 2015

          Essence of a Mustang

          Great exhaust with a deep aggressive and distinctive growl. The x pipe adds to the volume without adding any drone which is perfect for longer drives. Installation was easy however there was no getting around cutting, was a bummer however not a deal breaker. Would go as far as saying, if you own the new Mustang 5.0 GT AND don't have this exhaust. for shame! All in all very pleased.

          Alex

          Year: 2015 Submodel: GT Vaughan, ON

          Helpful (8)

        • 5/5

          Installation Time: Less than 1 Hour

          April 09, 2015

          Flowmaster American Thunder

          In love with this exhaust, couldn't be happier with my purchase. Very nice deep loping rumble at idle and really opens up when you get on it. Little to no drone at highway speeds. Love the sound while I accelerate at a normal rate, which is barely possible for me to do in this car, but you will know the people watching you just cruise off will just be begging you to punch it so they can hear it scream. If you want loud but just not sure quite how loud then I believe this is the exhaust for you. I was back and forth between this setup and the outlaw series and am definitely happy with this pick.

          BLK2015

          Year: 2015 Submodel: GT Texas

          Helpful (9)

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