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Flowmaster American Thunder Classic Axle-Back Exhaust (11-12 GT, 11-12 GT500)

62 Reviews
Our Price

$469.97

  • Item #18413
  • MPN# 817496

  • Market Price $531.07
  • You Save 12% ($61.10)
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Product Videos Customer Photos
Features
  • Aggressive Flowmaster Classic 40 Series Sound
  • Polished Stainless Steel 4" Tips
  • Durable 409 Stainless Steel Construction
  • Includes Two Flowmaster Mufflers
  • Fits 2011-2012 GT and 2011-2012 Shelby GT500 Mustangs
Description
Classic Flowmaster Sound. Give your 2011-2012 Mustang GT or GT500 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 two special 5" X 10" chambered Classic 40 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.

Application. This Flowmaster American Thunder Axle-Back exhaust system is designed to fit the 2011-2012 5.0 Mustang GT and 2011-2012 5.4L Shelby Mustang GT500 for both great looks and great sound.

Fitment: 2011 2012 Details

What's in the Box
Hardware included:
  • (2) Mufflers
  • (2) 3/8" Hanger Keepers
Installation Info
Tech Specs
Axle-Back Exhaust Specifications
Piping Material: 409 Stainless Steel Tip Material : Polished Stainless Steel
Piping Size: 3" Tip Size: 4"
Muffler Type: Chambered Fitment: 2011-2012 Mustang GT & 2011-2012 GT500
Will it fit my Mustang?
  • Boss 302 - 12
  • GT - 11, 12
  • GT500 - 11, 12

Most Helpful Reviews

5/5
Flow master American thunder

They sound great at cold start, and when you step on it. For the price they can't be beat . Took about an hour to install hardest part is factory cans are tacked. Other than that piece of cake. I would ...

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Helpful (1)

5/5
Monster Sound

Overall, I love this exhaust. I was looking for something that had a really deep rumble at idle and this is it. It also sounds fantastic at wide open throttle. My only complaint is that there is a bit ...

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Helpful (1)

Read All 62 Reviews
Overall Rating 4.7 out of 5 stars

Video

Hey everyone I’m Justin with AmericanMuscle.com and I’m taking a look at Flowmaster’s American thunder classic axle-back for your 2011 and newer Mustang GT. The American Thunder series axle-back is designed to give your Mustang that iconic Flowmaster sound, while giving you a little more horse power at the rear wheels. The system is constructed from durable 3 inch, 16 gauge aluminized tubing, and features 2 40 series chambered mufflers, everything is finished off with two 4 inch polished tips embossed with the classic Flowmaster logo. Now the installation itself should only take you about an hour using standard hand tools. Now lets see how Flowmasters American Thunder sounds compared to your factory exhaust.

Customer Photos (8) View All Photos

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1 Questions / 3 Answers

Ask a Question

Rear Valance I am thinking about getting Flowmaster American Thunder Classic Axle-Back Exhaust (11-12 GT, 11-12 GT500), but will I also need to change the rear valance as well? I have a 2012 GT /CS with stock everything now and was just wondering if I would have to do more mods to get the system. Any help would be greatly appreciated!

mustangbully

  • Your current rear valence set up will be fine, as the single outlet mufflers will fit thru the same space as your existing mufflers. Had you gone for the quad set up (2 outlets per muffler), then you would need the gt500 rear valence.

    Gtzzoom

    Good Answer (1) (0)

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Customer Reviews (62) Write a Review

Overall Rating 4.7

out of 5 stars




  • 5/5

    Installation Time: Less than 1 Hour

    April 04, 2013

    Monster Sound

    Overall, I love this exhaust. I was looking for something that had a really deep rumble at idle and this is it. It also sounds fantastic at wide open throttle. My only complaint is that there is a bit of a drone from 1300 to 2000 RPM. My stereo system is enough to take care of that though.

    JeremyW

    Year: 2012 Model: GT Driving Style: Daily Driver 'Stangs I have owned: 1 Nova Scotia, Canada

    Helpful (1) (0)

  • 5/5

    Installation Time: Less than 1 Hour

    July 16, 2012

    Flow master American thunder

    They sound great at cold start, and when you step on it. For the price they can't be beat . Took about an hour to install hardest part is factory cans are tacked. Other than that piece of cake. I would highly recommend these if your on a budget.

    RR1313

    Year: 2012 Model: GT Driving Style: Daily Driver 'Stangs I have owned: 2 Tx

    Helpful (1) (0)

  • 5/5

    March 18, 2011

    Great!

    Sound friggin awesome!The way my 5.0 SHOULD sound.Easy 45 min. install.Follow instructions and you can't go wrong.Nothing but compliments on how awesome my baby sounds now!!There is a little drone but not too bad in 6th at 1800-2100 rpms.Really nice when I drop the top and let my pony run.Drone is avoidable by shifting down to 5th or just leave it in 6th and ACCELERATE.

    Kozz

    Year: 2011 Model: GT Driving Style: Daily Driver

    Helpful (9) (0)

  • 5/5

    March 24, 2011

    rumble

    1.5 hr install time. mufflers tuck under car out of view. sound is deep but not 2 loud. upon start it rattles my garage door until i back out. u can feel it inside but can have a conversation easily. there is drone @ 2k but install jlt intake & tune then drone is gone. stomp the throttle on freeway and you will turn heads. hope this helps

    jason bradford

    Year: 2011 Model: GT Driving Style: Daily Driver

    Helpful (7) (0)

  • 5/5

    March 17, 2011

    BAMF!!!

    This exhaust has the deep rumble in low RPM's and that hollow mustang tone that we all love in the upper RPM's. In cab noise isn't bad at all, does drone a little bit around 2000rpm in 6th gear (3.73) but no complaints, just compliments from everyone who hears it. Install was very easy, 30 min tops. Its so simple you will try to over think the install. You will have to use the factory clamps so don't tear anything up while removing the factory mufflers. Wish i could give it more than 5 stars.

    Jake

    Year: 2011 Model: GT Driving Style: Daily Driver

    Helpful (9) (1)

  • 5/5

    August 08, 2011

    great exhaust system

    love the black as it hides the muffler from being seen from the back and underneath. I also think the quality and workmanship of the welds are great. i installed these in 1 hour and fifteen minutes and i am 66 years old laying under the back of the stang. i had to have another person help fit the drivers side into place because of the pan hard brace but still was not a big deal. i have an automatic and i really dont have any drone with these but they do sound great at idle and super at wot. btw the noise does not override my sync as a lot of aftermarkets do. i would highly recommend these to anyone for street use

    dan raab

    Year: 2011 Model: GT Driving Style: Daily Driver

    Helpful (7) (1)

  • 5/5

    Installation Time: Less than 1 Hour

    September 23, 2011

    Real Mustang sound.

    This Flowmaster system sounds great on my 2012 GT. It makes it sound like a mustang should sound. Fits up under car alot better than the stock system. Stainless tips fill up the cut out area much better. Ford should sell Mustangs this way. Installed in about 45 minutes. Great sound, great looks. A++++++++++++++++

    Fordman61

    Year: 2012 Model: GT Driving Style: Daily Driver 'Stangs I have owned: 3 Boise, ID

    Helpful (5) (0)

  • 5/5

    November 23, 2010

    Great Stainless Kit!!!

    Kit # 817496 compliments my 2011 5.0L to the fullest. It sounds amazing and the pricing is unbeatable. I cant believe I only paid 374.99 for a stainless kit!!! I would totally recommend this kit to any fellow 5.0L owner. The installation was very simple and painless, another great feature is the black paint. It allows the mufflers to blend in with the undercarriage of the vehicle. I was under the impression this kit was not stainless but it is, it's constructed out of a 409 grade stainless steel. Great American made product for a great price!!!

    Jerry

    Year: 2011 Driving Style: Daily Driver

    Helpful (14) (7)

  • 5/5

    Installation Time: Less than 1 Hour

    October 30, 2011

    A Classic Sound for a Classic Car

    I installed my flowmasters in just under an hour. After reading some of the reviews of previous users, I had my game plan set prior to install. NO Need to disconnect any type of bars underneath. I trimmed approx. 1/2" off one of the two rear hangers. (most inside hanger). I lubed the hangers prior to removal of old mufflers, and install of the new ones. The sound is iconic. Deep purr at idle. Nice and loud at WOT. The spot weld on the old mufflers?? No worries!! just bend them repeatedly to remove them. I jacked the car up maybe 4" to make it easier. I absolutely love these mufflers!!!! Great product!!!!

    SLEEPR

    Year: 2011 Model: GT Driving Style: Daily Driver 'Stangs I have owned: 1 FT. Bragg, NC

    Helpful (3) (0)

  • 5/5

    April 13, 2011

    It's all about the sound!

    My neighbor sees the box and says with a disgruntled look, “new exhaust huh?!" I'm thinking heck yeah! Got to love that old school rumbling sound! Well the installation was really easy and it looks and sounds great! This should be everyone's first purchase for their new Mustang, besides a lowering kit.

    Franciscus Ladage

    Year: 2011 Model: GT Driving Style: Street / Strip

    Helpful (4) (1)

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