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Flowmaster American Thunder Classic Axle-Back Exhaust (13-14 GT)

61 Reviews
Our Price

$456.48

  • Item #18443
  • MPN# 817588

  • Market Price $506.99
  • You Save 10% ($50.51)
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Product Videos Customer Photos
Features
  • Aggressive Flowmaster Super 44 Series Sound
  • Durable 409 Stainless Steel Construction
  • 2.75" Mandel-Bent Tubing
  • 4" Polished Stainless Steel Tips
  • Super 44 Series Mufflers
  • Direct fit replacement upgrade
  • Made in the USA
  • Fits 2013-2014 GT Mustangs
Description
Classic Flowmaster Sound. Give your 2013-2014 GT that unmistakeable Flowmaster sound with a nice power boost with the American Thunder Axle-Back exhaust system. This system improves exhaust flow using Flowmaster's patented chambered muffler design for that throaty, aggressive exhaust tone your high powered Pony deserves.

Quality Construction. Constructed from durable 3" 409 stainless steel tubing for its resistance to corrosion, the Flowmaster Axle-Back features (2) special 5" X 10" chambered Super 44 Series Flowmaster mufflers with 4" diameter polished stainless steel tips for muscle car looks and sound. As an added bonus, the tip is embossed with the "Flowmaster" logo for true custom styling.

Direct Fit Upgrade. This Flowmaster American Thunder Classic Axle-Back Exhaust includes all the hangers and clamps needed to bolt up in the stock factory location without any modifications required, making it a direct fit replacement upgrade.

Application. This Flowmaster American Thunder Axle-Back Exhaust System is designed to fit the 2013-2014 GT models equipped with the Coyote 5.0L 4V V8 engine.

Fitment: 2013 2014 Details

Won't fit? Add an exception

What's in the Box
  • (2) Mufflers
  • (2) 3/8" Hanger Keepers
Installation Info
Tech Specs
Axleback Exhaust Specifications
Piping Material: 409 Stainless Steel Tip Material : Polished Stainless Steel
Piping Size: 3" Tip Size: 4"
Muffler Type: Chambered Fitment: 2013-2014 GT 
Will it fit my Mustang?
  • Boss 302 - 13
  • GT - 13, 14

Most Helpful Reviews

5/5
These Flowmaster axle-backs are amazing!!

I purchased my first Mustang (a 2013 GT) in late November. I absolutely love the car, but there were a few mod’s I definitely wanted to make right away. The first mod on my list was a new exhaust. The ...

Read More
Helpful (6)

5/5
Simply Amazing

I pulled off the stock mufflers (to the tune of 46 pounds for the pair) and slipped the Flowmaster American Thunders under the 2014 GT that I just picked up. The first thing that was noticed, was that ...

Read More
Helpful (4)

Read All 61 Reviews
Overall Rating 4.8 out of 5 stars

Videos

Hi I’m Justin with AmericanMuscle.com, and I’m taking a closer look at the American Thunder classic axle back exhaust fitting the 2013 Mustang GT and GT500. The classic from Flowmaster gets its name from View Full Transcript

Customer Photos (12) View All Photos

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2 Questions / 4 Answers

Ask a Question

Do you need a tune after install?

2013StangDC Year: 2013 Model: GT

  • No Tune needed, Just enjoy the sound!!!

    Best Answer

    Beerz Year: 2013 Model: GT Top 500 Contributor

    Good Answer (1)

Show 2 more answers Question Resolved

I'm wondering if the American thunder is the 60 delta flow muffler or the 44 series? In the video for the force 2 Justin says that the American thunder is the 60 series. I want the 60 series not sure which one to purchase. Thank you

Robert Year: 2014 Model: GT

  • 44 series sound the best

    bill2014 Year: 2014 Model: GT Top 250 Contributor

    Good Answer (0)

Question Resolved

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Customer Reviews (61) Write a Review

Overall Rating 4.8

out of 5 stars

Installation Time:Afternoon

Installation Cost:0-$100

  • Loudness / Volume 4.672131 4.7
  • Exhaust Note 4.770492 4.8
  • Fit & Finish 4.852459 4.9
  • Bang For Your Buck 4.655738 4.7



  • 5/5

    Installation Time: Afternoon

    January 23, 2013

    These Flowmaster axle-backs are amazing!!

    I purchased my first Mustang (a 2013 GT) in late November. I absolutely love the car, but there were a few mod’s I definitely wanted to make right away. The first mod on my list was a new exhaust. The factory exhaust didn’t give the powerful muscle car sound I wanted and expected. This is my first Mustang (and first Muscle car), so I did a lot of reading and watched a lot of youtube videos to find out what might be best for the sound I’m looking for. I decided to go with the Flowmaster American Thunder; which I am so happy I choose! They sound AMAZING! From inside the car, I can definitely hear a deep, rumble in the lower RPM’s and when I get on it, my baby roars! Not an annoying moan, but a low, rumble like you’d expect to hear from a race car. Heads are definitely turning now! :) The installation was fairly easy – It took just over an hour. Getting the factory mufflers off was a little hard to do on my own, but I was able to handle it. There were no surprises, but having an extra set of hands would be helpful and backing the rear wheels up onto something to lift it 6 inches or so is recommended for easier access and room to work. I highly recommend purchasing the American Thunder – The price is good and they sounds great. You won’t regret the purchase. Next on the list is a cold air intake, then a tune! AmericanMusclecom is my new favorite website!!

    SELENE2013

    Year: 2013 Model: GT Driving Style: Daily Driver 'Stangs I have owned: 1 Beaverton, OR, USA

    Helpful (6) (0)

  • 5/5

    Installation Time: Less than 1 Hour

    April 08, 2013

    Simply Amazing

    I pulled off the stock mufflers (to the tune of 46 pounds for the pair) and slipped the Flowmaster American Thunders under the 2014 GT that I just picked up. The first thing that was noticed, was that the Flowmasters fit under the car so much better than stock. They don't hang below the rear valance and draw attention to themselves like the stock setup. Also, the full 4" tips fill out the exhaust cut-outs so much more appropriately. Then, I fired the car up. American Muscle does an outstanding job with their videos, but even they don't do justice to the throaty rumble coming from the back of the car. Night and day over stock. Great investment!

    Red14

    Year: 2014 Model: GT Driving Style: Daily Driver 'Stangs I have owned: 1

    Helpful (4) (0)

  • 5/5

    Installation Time: Less than 1 Hour

    June 11, 2013

    This is what a Mustang 5.0 GT should sound like !!

    I took my time trying to compare many of the videos , stock exhaust to the Flow Master products, I didn't want the wrong kind of attention so I knew i didn't want the straight pipes. These American Thunder series sound sweet, as soon as it fired up a big smile came over me. but I also noticed a few other nice things happening. The engine obviously is breathing much better, I can feel a welcomed crisper response on the throttle, the fuel economy actually went up 1 tick " or " point one or .1 was getting 19.3 MPG and as soon as i got a test run on the new pipes it went to 19.4 MPG AVG . I am 100% satisfied with these pipes. LOVE EM !!!

    VolumetricEfficiency

    Year: 2014 Model: GT Driving Style: Daily Driver 'Stangs I have owned: 2 Alabama

    Helpful (2) (0)

  • 5/5

    Installation Time: Less than 1 Hour

    November 10, 2012

    Flowmaster American Thunder Classic Axle-Back

    The installation of the mufflers was easy overall, but I did need an extra set of hands to help me push the pipes back to get the factory mufflers off. Once this was done, putting the new mufflers on went without a hitch. I already have a set of these on my 2012 5.0, so putting these on my wife's 2013 5.0 went much smoother. This exhaust added a much meaner sound to our Ponies! I would recommend these to anyone who is looking for an upgrade to their exhaust.

    Alfred

    Year: 2013 Model: GT Driving Style: Daily Driver 'Stangs I have owned: 3 Houston, TX, USA

    Helpful (3) (1)

  • 3/5

    Installation Time: Afternoon

    March 03, 2015

    Unpleasant sound

    This is my second Flowmaster axle-back system. The first one was a Force II. Loved it. However, this American Thunder system is a quantum leap in terms of noise. It's very loud, which I would have been OK with had it not been to an overpowering DRONE around 2000 RPM's. The drone is very pronounced and I'm not happy. I'm considering putting the stock system back on it. In fairness I do like the exhaust note under full throttle. It's great! Sadly it doesn't make up for the painful resonance at cruising speed.

    Top 1000 Contributor

    Hoop

    Year: 2014 Model: GT 'Stangs I have owned: 1 Rossville, GA

    Helpful (1) (0)

  • 5/5

    Installation Time: Less than 1 Hour

    December 24, 2014

    Sound great, super easy install.

    I shopped around for quite a while to find the right axle backs, listening to clips, reading reviews, etc. I went with these because they had a good sound and no loud raspy sound under throttle. They are perfect in my opinion, the fit is excellent and took me about 30-40 mins to install using a set of ramps and a ratchet. I'd consider myself above average on mechanical ability, but even a novice should be able to handle it in less than 2 hours for sure. There is no drone that I can find, I went through the gears and cruising 50-75mph in 6th gear. If you want an aggressive sound without being irritatingly loud, these are perfect. The sound clips on this site represent it pretty well, but they are a bit louder in person, which is what I hoped for. I couldn't be happier with these, and the folks at American Muscle got them here faster than I expected, ordered on a Saturday and at my door, from Pennsylvania to Louisiana, Tuesday morning. Packaged well, tips protected, definitely recommend the mufflers and American Muscle. I will be buying anything I need or want for my car from here.

    TimFromBama

    Year: 2014 Model: GT Driving Style: Daily Driver 'Stangs I have owned: 5 Louisiana, USA

    Helpful (1) (0)

  • 5/5

    Installation Time: Less than 1 Hour

    September 09, 2014

    Keep that true mustang sound!!!

    The American thunder axel back is awesome. I've had a 14 GT for a month and a half and couldn't wait to put an exhaust on. I was between the pypes pipe bomb, the flowmaster outlaw and the American thunder. I did a lot of research and listened to a lot of you tube videos cause I had never heard any of these three axel backs in person. Let me just say if your between those three just stop your research and get the American thunders. They sound unbelievable. They really keep the mustang sound just make it deeper and louder. The installation was a piece of cake with an extra pair of hands and a lift. About fifteen minutes. They have an awesome idle and they don't make it easy to keep your foot off the gas. There is a slight drone at 2000 rpm but with a manual you can adjust whether you want to hear it or not. Personally I kind of like it. Makes me feel like I'm actually in a mustang. Fitment was perfect and I'm actually starting to turn heads. And you don't have to worry about waking the neighbors its not obnoxious and wont attract the wrong kind of attention. I highly recommend these axel backs. Thanks AM for helping me with my first mod.

    Baller31

    Year: 2014 Model: GT Driving Style: Daily Driver 'Stangs I have owned: 1 Asheville, NC, USA

    Helpful (1) (0)

  • 3/5

    Installation Time: Afternoon

    June 08, 2014

    too much drone

    The exhaust note was awesome and the loudness was good, but the droning inside the car was unacceptable. It occurred even on light acceleration, so just poking around town was noticeable (though tolerable). But highway driving would give you a headache! Some guys don't mind the droning, but it bothered my middle-aged sensibility. Think carefully before forking over the money since you can't return it. Afterward, I spoke to the sales rep. He was very helpful and steered me toward a Borla. Should have talked to him first.

    wwsGT

    Year: 2014 Model: GT Driving Style: Daily Driver 'Stangs I have owned: 1 Carlisle, PA, USA

    Helpful (1) (0)

  • 5/5

    Installation Time: Afternoon

    May 13, 2014

    Now that's what I call a premium sound system!

    This is the first real mod that I have performed on my 2014 GT. I was looking for a louder and more distinct sound from my ride and I am thrilled with the results. The online guide to installation was pretty good, and I did it in a little over two hours. The most difficult job was removing the old axle back as space to pull it off is pretty tight. The difference in the exhaust note is quite evident, a much more "throaty" quality at start up, and a very nice rumble when cruising at low speed. When I punch it, I am rewarded with that sound only a Mustang can make, and the way it resonates when you downshift is very satisfying. Heads definitely turn when I drive by. I was a little concerned about the drone some reviewers have experienced. Although I do notice what you could describe as a drone at about 1600 rpms, it is not what I consider irritating or even significant. Overall I am very satisfied with the Flowmaster American Thunder Classic.

    barnacle989

    Year: 2014 Model: GT Driving Style: Daily Driver 'Stangs I have owned: 5+ Columbus, OH, USA

    Helpful (1) (0)

  • 5/5

    Installation Time: Shop Install

    Installation Cost: 0-$100

    June 25, 2013

    Great Sound!!!

    I just received these in the mail Yesterday, I Took them to Midas and Steve Installed them for me for 47.00. Very glad I took them there, as I helped him install these I realized it would have really sucked to do this in my Garage. On a lift it's a little bit of a pain to get the stock ones off, on my back it would of been a real bad day. Once they are on though, the smile stretches from ear to ear, sounds so Deep and Throaty! This should be the stock sound, Love everything about it. Wife hates them so I know I did good! The Drone is acceptable, I just love this sound!

    Top 500 Contributor

    Beerz

    Year: 2013 Model: GT Driving Style: Daily Driver 'Stangs I have owned: 2

    Helpful (3) (2)

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