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

Market Price $563.99 You Save 12% ($65.23)
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$498.76

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  • Item 18413
  • MPN# 817496

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    Features, Video & Details

    • 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

    Review & Installation Video

    Review & Install 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.

    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

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

    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?

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    Questions & Answers (4)

    4 Top Rated Questions

    Will this fit a 2014 5.0?

    • 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 only.

    Helpful (0)

    I own a 2013 v6. Will these fit? Thank you for your time and assistance.

    • Unfortunately, this Flowmaster American Thunder Classic Axle-Back Exhaust is specifically designed for use on 11-12 GT and GT500 model Mustangs, so it will not fit your 2013 V6.

    Helpful (0)

    i have the outlaw series cat back will these mufflers bolt up to the outlaw exhaust the outlaw series mufflers are too loud with the long tube headers

    • Yes, The piping will step down to allow for the axle back to be interchanged from the Flowmaster Outlaws to the Flowmaster American Thunder Classic Axle-Back Exhaust.

    Helpful (0)

    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!

    • 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.

    Helpful (0) Show 2 more answers
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    People Who Bought This Item Also Bought

    Customer Reviews (67) Write a Review

    Overall Rating 4.6

    out of 5 stars

    Installation Time:Less than 1 Hour

    Installation Cost:$100-$250

    • Loudness / Volume 4.442307 4.4
    • Exhaust Note 4.653846 4.7
    • Fit & Finish 4.692307 4.7
    • Bang For Your Buck 4.392157 4.4



    • 4/5

      Installation Time: Shop Install

      Installation Cost: $100-$250

      January 02, 2018

      Sound great

      These have the sound I was looking for, but they would not mate up to the 3” after market pipes in my Stang. I had to take to a custom shop and Pay $150 to have them welded on. Now they look good and sound great. Had Pype Bombs on it before and they were just way too loud.

      Jack99

      Year: 2012 Submodel: GT

      Helpful (4)

    • 5/5

      Installation Time: Less than 1 Hour

      November 04, 2017

      Sound Amazing

      These axlebacks slund amazing . Alot better than stock for sure

      JNich

      Year: 2011 Submodel: GT

      Helpful (3)

    • 2/5

      Installation Time: Afternoon

      October 10, 2017

      Damaged

      the flowmaters sent to me I received were damaged on the mounting flanges (huge flat spots) the packing was poorly done the mufflers were able to move freely I had to machine a die to rework the flange angle otherwise they would never had seated properly they are mounted with no leaks I shouldn't have to fix a product I paid hard earned money on...

      PHILIP

      Year: 2012 Submodel: GT

      Helpful (3)

    • 2/5

      Installation Time: Afternoon

      September 02, 2017

      Very loud mufflers

      These mufflers are rated as quieter but they are actually extremely loud. Going through residential areas I had to feather the gas pedal to make sure no cops would notice me. I had to add another set of mufflers in front of the differential to cut the noise down and they are still very loud. However, they sound good at idle and at WOT

      PierreP

      Year: 2011 Submodel: GT

      Helpful (3)

    • 5/5

      Installation Time: Less than 1 Hour

      June 08, 2017

      Very nice sound

      A beautiful sound that gives character to my Mustang

      BrunoC

      Year: 2011 Submodel: GT

      Helpful (3)

    • 5/5

      August 02, 2016

      There everything I though they be

      I love the Flowmaster American classic if you like deep rich sound the Flowmaster is the one for you putting this puppy's in is just about a 1hr job getting the mufflers out of the hangers is the hardest part but the fight is well worth it if by them you will injoy

      One909

      Year: 2011 Submodel: GT

      Helpful (4)

    • 5/5

      July 06, 2016

      WOW!!!! Amazing sound

      I was always a fan of the fox body Flowmaster sound! So when I got these for my 2011 GT500 that's what I was hoping for and WOW!! Love the sound all around, sounds great starting up, at idle and it has a monsterous sound under acceleration! So happy I got these!!!

      EricJ

      Year: 2011 Submodel: GT500

      Helpful (3)

    • 5/5

      Installation Time: Less than 1 Hour

      March 18, 2016

      Get it. You'll love it.

      These sound great. Loud when you want it. Quiet when cruising. Easy install.

      NEMO

      Year: 2012 Submodel: GT

      Helpful (3)

    • 5/5

      Installation Time: Less than 1 Hour

      February 22, 2016

      pmo

      I put the flow master exhaust om my 2011 mustang gt 5.0 it sounds good and fast I would recommend into all my mustang buddys

      paul

      Year: 2011 Submodel: GT Zanesville Ohio

      Helpful (3)

    • 5/5

      Installation Time: Less than 1 Hour

      October 26, 2015

      Flow maser

      Great product, looks great and sounds awesome. Fit was great also

      JJ

      Year: 2012 Submodel: GT Chattanooga

      Helpful (3)

    • 2/5

      Installation Time: Less than 1 Hour

      May 14, 2015

      Not What I Wanted

      I have a 12 with an automatic. At 1700 to 2100rpm the drone is so loud you can't ave a conversation in the car. Shift point and interstate speed falls right in this drone range. At cruise speeds around town the deep rumble is awsome and the idle rumble takes me back to the day. I just can't handle the drone so I'm planning on replacing these mufflers with something with less drone. Flowmaster missed it with these mufflers. I have had two other cars with Flowmaster mufflers and enjoyed them both but not these.

      Manon

      Year: 2012 Submodel: GT Louisville KY

      Helpful (5)

    • 4/5

      Installation Time: Afternoon

      October 21, 2014

      Loud, Deep, Powerful

      I will say the Thunder Classic is everything as promised -- loud, deep, and powerful sounding; however, I gave it an overall lower rating (4 stars) and average exhaust note rating (3) because of the very intense and relentless drone at all speeds & rpms. There really is no point at which your ears get a rest from the drone, so it just takes some getting used to, but man does it sound great when you jump on it !!! **It is also important to note that I have this exhaust paired with a JBL CAI and bama tune, so I don't know how that is potentially effecting the intense drone described above.

      Bigstick

      Year: 2012 Submodel: GT

      Helpful (3)

    • 5/5

      September 05, 2014

      Make your coyote bark.

      Just installed the Flowmaster American Thunder Classic Axle-Back Exhaust on my 2012 GT. The first start was excellent, that raspy growl can't be beat. Took longer than an hour, but that's Ok. I removed the stock mufflers and brackets as one piece. Makes it easier to wrestle the rubber over the nub on the hangers. The install was super easy, plenty of room to reach the bolts. A lot lighter than the stock pieces. Follow the instructions and its cake.

      Yokmoni

      Year: 2012 Submodel: GT Illinois

      Helpful (3)

    • 5/5

      Installation Time: Afternoon

      August 24, 2014

      sounds like car looks

      very happy with product. loud, but not too over the top. looks a lot better than stock. took 3 hours, with a few tools. car not the same with stock exhaust.

      rick44444

      Year: 2011 Submodel: GT phila. pa.

      Helpful (3)

    • 4/5

      Installation Time: Less than 1 Hour

      June 09, 2014

      These axlebacks have a nice growl!

      Worth the money, sounds great, the drivers side tip was a little off center for the drain hole for condensation but other than that it all looks good and has the growl I was looking for! Thanks!

      mergasmerga

      Year: 2012 Submodel: GT Junction City, KS, USA

      Helpful (3)

    • 5/5

      Installation Time: Less than 1 Hour

      September 25, 2013

      Awesome sound

      Awesome sound I'm currently running an off road H-pipe with these axlebacks.Deep sound with no rasp, and there is minor drone then what everyone else is saying. A must buy for your stang!

      Lozo5OH

      Year: 2012 Submodel: GT West Palm Beach, FL, USA

      Helpful (6)

    • 5/5

      Installation Time: Less than 1 Hour

      August 15, 2013

      Not too loud, great mean rumble, just what I was looking for!

      Great sounding exhaust. I was looking for something that was loud enough for people to hear but not so loud that I cant hear myself think on the highway. This was the perfect exhaust for that. looks great, sounds great, and its affordable. I recommend it!

      liquidsilver

      Year: 2011 Submodel: GT Southwest Mo

      Helpful (3)

    • 2/5

      Installation Time: Afternoon

      July 19, 2013

      Product gives too much interior drone

      I expected a great exhaust note based on my 2008 GT that had the same system. The exterior sound on my 2011 is excellent but the interior sound is unbearable. I am switching to a Ford Racing GT500 Axle back hoping to tone down the interior drone. If not, its back to stock.

      Lowball

      Year: 2011 Submodel: GT North Carolina, USA

      Helpful (4)

    • 5/5

      Installation Time: Less than 1 Hour

      May 15, 2013

      Flowmaster American Thunder Classic Exhaust 2011 GT

      The fit was flawless; had to remove the muffler clamp from the stock mufflers, but it wasn't any problem. They are spot welded to the pipe; just bend the strap back and forth until it breaks and reuse the clamp on the new mufflers. The sound is really great - pretty much what I expected and what the car should have sounded like in the first place. The other reviews mentioned a drone at around 2000 rpm - it's there alright, especially when under load. It can drown out the sound system, but I'm fine with that. Now I drive with the windows down just to hear the sweet thunder. Great product, just wish it wasn't priced so high.

      MikieLikesIt

      Year: 2011 Submodel: GT Crowley, TX, USA

      Helpful (3)

    • 5/5

      Installation Time: Less than 1 Hour

      May 13, 2013

      WOW. Thats what a 5.0 should sound like

      Read directions first-LOL. Very easy install when you unbolt cross member. Make sure you lube hangers and its a sinch. Very nice fit. Very agressive at idle, sounds very old school.Crusing is very tolerable. Highway is tame until you hit the gas. I didnt really here the drone at 2000 rpm. If you have a stick, its very hard not to rev the rpms all the time. wow amd I happy with this purchase. Nice job FLowmaster.

      sfistang

      Year: 2011 Submodel: GT Temperance, MI 48182, USA

      Helpful (3)

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