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Flowmaster Force II Axle-Back Exhaust - Aluminized Steel (05-10 GT, GT500)

Market Price $497.99 You Save 13% ($65.02)
Our Price

$432.97 (pair)

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  • Item 18403
  • MPN# 17410

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Features, Video & Details

  • Aggressive Flowmaster 60-Series Delta Flow Sound.
  • Polished Stainless Steel 4" Tips.
  • Durable Aluminized Steel Construction.
  • Includes Two Flowmaster Mufflers
  • Fits 2005-2010 GT and 2007-2010 Shelby GT500 Mustangs.

Review & Installation Video

Review & Install Video

I’m Justin with AmericanMuscle.com, and this is our detailed breakdown of Flowmaster’s American thunder series Axle-back for the 2005-2010 Mustang GT. This kit from Flowmaster centers around those patented classic 60 series delta mufflers that are responsible for that iconic Flowmaster muscle car sound and rumble. Flowmaster is one of the only companies that chooses to use 16-gauge aluminized steel for their exhaust versus stainless steel. Now that coated steel is going to be great for resisting corrosion, and that sleek black finish is going to look really sharp underneath the rear bumper. Now the entire kit is finished off with these dual 4” tips and embossed with that iconic Flowmaster logo. Getting the American Thunder bolted up to your ride is a very straightforward task that should take you no more than an hour using some basic hand tools. Now let’s see how Flowmaster’s American Thunder sounds compared to our factory exhaust.

Flowmaster Sound. The Flowmaster Force II Axle Back exhaust system, with it's patented 60 Series Delta Flow chambered mufflers will improve your GT or GT500 Mustang exhaust flow for an increase in power and a throatier exhaust note.

Quality Construction. Constructed from durable 2.5" 16 gauge aluminized steel tubing for it's corrosion resistant properties the Flowmaster Axle Back features specialty 5" X 10" chambered 60 Series Delta Flow Force II Mufflers with massive 4.0" diameter polished stainless steel tips for muscle car looks and sound. As an added bonus the tips are embossed with the "Flowmaster" logo for true custom styling.

Fitment. This aluminized steel Flowmaster Force II Axle-Back Exhaust System is designed to fit the 2005-2010 GT and the 2007-2010 Shelby GT500 Mustangs for both great looks and great sound.

Technical Note: Americanmuscle recommends adding the 2005+ Mustang 304 Stainless Steel Exhaust Hanger Kit from the drop down option above, to provide more strength, stability and a cleaner installed appearance. If you have a 2007 Mustang you may need the kit for correct installation.

Fitment: 2005 2006 2007 2008 2009 2010 Details

What's in the Box
  • (1) Right muffler assembly
  • (1) Left muffler assembly
  • (2) Clamps
  • (1) Nut
  • (1) Lock Washer
Installation Info
Tech Specs
Axle-Back Exhaust Specifications
Piping Material: Aluminized Steel Tip Material : Polished Stainless Steel
Piping Size: 2.5" Tip Size: 4.0"
Muffler Type: Chambered Fitment: 05-10 GT, GT500 Mustangs
Will it fit my Mustang?
  • Bullitt - 08, 09
  • GT - 05, 06, 07, 08, 09, 10
  • GT500 - 07, 08, 09, 10

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Most Helpful Reviews

easy install- very good service

nice quiet sound from the roush resonators. fit under pretty good. the price is better than the other suppliers.

Helpful (4)

Nice sound for a V6

I installed these on my 06 Mustang V6 behind a Mac Pro Chamber cut and clamp with original cats and exhaust manifolds in place. It gives a nice mellow rumble (almost a rumble) to the exhaust. It's gets ...

Read More
Helpful (1)

Overall Rating 4.7 out of 5 stars
Read All 100+ Reviews

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11 Questions / 8 Answers

Ask a Question

Will this work? Can i use these axle back exhaust on my 05 v6 mustang if i purchase the pypes x pipe?


  • The short answer is no. I would suggest buying a V6 True Dual Exhaust conversion kit. That way you get all the parts necessary for converting your entire exhaust system.


Show 1 more answer Helpful (1)

How does the aluminized steel hold up to high temps? I have an 08 with long tube headers and no cats. I have the black pype bombs on now, and the powder coating is flaking off due to excessive exhaust temps.


  • The Flowmaster American Thunder Axle-Back Exhaust does come with a light powder coating on it that does hold just fine to high heat.


Helpful (0)

Do I have to buy the hanger kit or can I use my stock hangers and save the cash? Thanks.


  • While the Flowmaster American Thunder Axle-Back Exhaust (05-10 GT, GT500) recommends the use of the SR Performance Stainless Steel Exhaust Hanger Kit (05-10 All) item #20021 http://www.americanmuscle.com/pypes-2005-stainless-hangers.html, it is not required. As long as your existing exhaust hangers are in decent shape you can use the ones on your Mustang. Hope this helps!


Helpful (0)

Hi everyone! I am kind of confused because of the product information. The price says €380.12 for me (each). Does "each" mean left and right in each case €380.12 or does "each" mean the complete muffler-system (including both)? Because further down it says both mufflers are in the box. Kind regards gzunlimited


  • The Flowmaster American Thunder Axle-Back Exhaust (05-10 GT, GT500) are sold as a pair. The price of $420.97 will be the price for both left and right mufflers.


Helpful (0)

Does this exhaust sound good on an automatic (05-10 GT) ?


  • just had the flowmasters installed in a 05 auto,convertible they sound great


Helpful (0)

Will these fit on an 08 GT CS?


  • Works on my '09 GTCS. Sound great!


Show 1 more answer Helpful (0)

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Customer Reviews (100+) Write a Review

Overall Rating 4.7

out of 5 stars

Installation Time:Afternoon

Installation Cost:0-$100

  • Loudness / Volume 4.1875 4.2
  • Exhaust Note 4.594594 4.6
  • Fit & Finish 4.473214 4.5
  • Bang For Your Buck 4.594594 4.6

  • 5/5

    Installation Time: Less than 1 Hour

    November 12, 2013

    Nice sound for a V6

    I installed these on my 06 Mustang V6 behind a Mac Pro Chamber cut and clamp with original cats and exhaust manifolds in place. It gives a nice mellow rumble (almost a rumble) to the exhaust. It's gets decently loud at WOT but has a good clean almost muscular sound. There is a slight drone but it is a tolerable, almost enjoyable drone. I'll add that I started with take off GT mufflers, then swapped them for Pypes Pype Bombs. The Pype Bombs were way too loud and had a terrible drone on the V6. These however add a great dimension to the exhaust note and I highly recommend them for the V6'ers looking for a decent clean sound that draws attention when you get on it..


    Year: 2006 Submodel: V6 Egg Harbor Township, NJ, USA

    Helpful (1)

  • 5/5

    Installation Time: Less than 1 Hour

    September 30, 2011

    easy install- very good service

    nice quiet sound from the roush resonators. fit under pretty good. the price is better than the other suppliers.


    Year: 2010 Submodel: Other billings mt.

    Helpful (4)

  • 5/5

    August 04, 2011

    Gives my V6 Exhaust a Nice Deep Muscule Tone

    For my 21st birthday, I decided to treat myself to an 05 mustang v6. Yea I know it's not a GT but like many others, initial cost and gas were factors in my decision since I am a college student on a budget. Anyhow, true dual exhaust was my first performance upgrade to my Mustang. After taking into consideration cost and watching a LOT of sound clips, I opted to go with Flowmaster American Thunders (more about my setup later). American Muscle was able to do the one day shipping for me for only $11 or so, so kudos to you guys at A.M! I knew from the sound bites that the car would sound pretty good. I never thought it would sound this good! Pros: * moderately loud but deep tone (can't say it's V8, but it does sound amazing) * loud when accelerating, but quiets down at cruising..perfect for me * good interior sound for the majority * decently priced * car seems to accelerate faster (do not have dynos to prove yet, just comparing feel) Cons: * initial drone every so often(given I just got these put on yesterday this is expected, hopefully after I break them in it will stop) Overall I am glad I did my research and went with the A.Ts. My thanks to A.M and Flowmaster! Oh by the way, here is my exhaust setup: * stock v6 * stock manifolds * custom h pipe * 2.5" piping * Flowmaster American Thunder mufflers


    Year: 2005 Submodel: V6

    Helpful (4)

  • 5/5

    May 05, 2011


    I took approximately 3 months to decide what exhaust modification to use in my 2009 Mustang Gt. I talked to other owners, read blogs and performance comparisions, and listened to sound comparisions on youtube, other sellers sites, and of course American Muscle. I chose the Flowmaster American Axle-Back Exhaust system with aggressive sound for my car, and boy what a difference in performance and sound they made. Everyone who has heard them says they are simply AWESOME! Can't beat American Muscle's price.

    Dave Aken

    Year: 2009 Submodel: GT

    Helpful (4)

  • 5/5

    April 20, 2011

    rusty muffler

    bought a pair flowmasters 3 years ago. aluminised on the outside.rusted on the inside. shouldhave bought stainles ones.have not bought new yet.

    joe s brinkman

    Year: 2007 Submodel: GT

    Helpful (1)

  • 5/5

    January 23, 2011

    Boo price drop

    I bought these for christmas. Went on fairly easy, passenger hangs a little low but so did my stock exhaust, its just a little more noticeable with the huge tips. have put almost 1000 miles on them and they are really starting to sound sweet. The price dropped almost $50 the week after I bought them which sucks but... I am pleased thought they weren't going to be loud enough at first, sounds great but not really loud. Third gear pulls harder than it did before which is nice.... Slight issue with leaks around the clamps provided by Flowmaster, stock clamps wouldn't come off original axle-backs. Overall, great product, if you are looking for something to give your stang a little more kick and a more throaty sound with out sounding ragged out these are the ones.


    Helpful (1)

  • 5/5

    August 07, 2009

    09 GT

    I had been waiting for flowmaster to come out with bolt-on mufflers since i bought my car, and man it was worth the wait. sounds great and it was easy to install


    Year: 2009 Submodel: GT

    Helpful (5)

  • 4/5

    August 02, 2009

    09 Mustang GT

    Lots of droning at first. needs about 1 month to fully break in. Recommend welding arounf the clamps to keep water out, and ensure good seal. Otherwise real easy install and sounds real good.


    Year: 2009 Submodel: GT

    Helpful (3)

  • 5/5

    June 18, 2010

    Good Sound

    Very nice product, produces just enough sound to give a nice rumble and not tick off the nieghbors. Excellent fit and the large tips look great coming out the back.


    Helpful (37)

  • 5/5

    March 15, 2010


    flowmaster AT took about an hour to get on, including removal of stock mufflers. the fit was spot on after a bit of hammering to shape. sounds FANTASTIC! i feel sorry for mustangs next to me when the light turns green. anti-sieze was a big help during installation and having a ramp to get the car up was a necessity. great product, best price, super fast shipping, buy from american muscle.


    Helpful (7)

  • 5/5

    November 20, 2010


    Love the Flowmasters. Installed myself in about 1.5 hours without a jack in my apartment garage. Hardest part was removing the stock mufflers. Great sound but initial drone made me nervous that I had made the wrong decision. After about a month the drone has gone away and the exhaust sounds more muscular. Nice and quiet when cruising down the highway, but growls when you get on the gas. Great combination for every day driving. Would recommend to everyone. This is how they should have came stock!


    Helpful (25)

  • 5/5

    April 06, 2010

    Buy This

    I recently put this system on an 07 GT. The only minor problem i had was that the end of the pipe on the inlet of the new mufflers was slightly out of shape. Easily fixed with a little hammering. Aside from that, easy install, fits perfect. Sounds perfect!!! Much like my opinion of the cars style, this system sounds like a perfect blend of muscle car and new car. It's loud when you want it to be, but you can keep it pretty quiet if you want to hear the radio or are driving through town. I definitely recommend this over competitors, the price is hard to be as well


    Year: 2007 Submodel: GT

    Helpful (14)

  • 4/5

    March 16, 2010

    Sounds Amazing

    I installed these on my 2010 and my buddy's 2007 and they sound great. The installation was fairly quick and they fit like a glove. One of the mufflers came with the inlet hammered up (probably due to shipping) so we had to fix that. I was also happy to discover that there is no "droning" with these mufflers, I was afraid they would. You can't beat the sound of these mufflers for the price you pay.

    Johnny Pounder

    Year: 2010

    Helpful (14)

  • 4/5

    June 30, 2009


    its about time they carried flowmasters!!! freakin love them... a little droning in the beginning aroud 2100 grand... after they get broke in, they\'re AMAZING!!!


    Helpful (16)

  • 5/5

    May 23, 2011


    After much debate and sound clips I chose the American Thunder. I was originally going with the Borla Stinger S-Type, but had a hard time justifying that coin for a couple mufflers. Got an email from American Muscle....$269 I took a gamble on a bargain and I can honestly say this is one of those times the bargain actually pays off! At idle it is slightly louder than stock with a much deeper tone. Ease off the clutch and it comes to life with a mellow growl. At full throttle it sounds like a muscle car, and anyone who has been behind it compliments me on the sound. Highway mode is awesome, it is equally if not more quiet than stock. If you want it to sound great when on the gas but not drone your brains out this is the system for you. I only have the axleback and have no plans to change. If you want everyone to stare at you and dont mind it sounding like a ricer go with something else...and please sell your mustang.


    Year: 2005 Submodel: GT

    Helpful (23)

  • 5/5

    August 20, 2010


    I have a 2010 mustang gt, I ordered this thinking that it would mot make much of a difference, well i was very wrong. The sound is a night and day difference from the stock exhaust. The sound is just strong feeling, there are no words that can decribe on how happy i im with this.

    Justin N

    Year: 2010 Submodel: GT

    Helpful (21)

  • 5/5

    January 12, 2011

    Flowmaster Axle-Back

    Awesome product! Having a ramps, lift, or jack would definitely help with install. Some suggestions though if you go with these go buy high temp paint and paint them up before you install them, the black finish flakes off super easy. Second thing, if you can take the stock clamps off if you can. The supplies clamps don't seem to tighten down as much as the stock ones do. Overall the Flowmasters sound awesome though and I would definitely recommend.


    Helpful (9)

  • 4/5

    May 26, 2010

    Acel Back Exhaust

    I put the axel back exhaust on my 07 GT. Very easy installation, and it sounds great. Produces the "roar" that I was looking for.


    Year: 2007 Submodel: GT

    Helpful (10)

  • 5/5

    August 15, 2010

    Flow masters

    works great with bbk long tube headers an catted x pipe


    Helpful (7)

  • 5/5

    May 03, 2011

    American Thunder

    I had my neice's husband install them for me, figuring since he is a former auto mechanic would be abled to solve any problems that would arise when installing the Flowmaster mufflers. He did not use car ramps or jack stands, he only detached the back muffler hanging straps,the muffler clamp attached to the mid pipe was loosened, he had to wiggle the muffler abit to detach it from the mid pipe. There is a spot weld on the clamp that is on the muffler, he took a hammer and proceeded to hit the clamp on the top and the bottom a couple of times until the spot weld came undone. I detached the negative terminal on the battery for 2 mintues so that the car computer could adjust itself to the increased air flow. I started the car up,it was a little bit louder than the stock mufflers, crusing down the hiway it is quiet, but when you hit the pedal to the metal you can hear the engine growl, it made me laugh abit, this is the way the car should sound like when coming off the assembly line. So far I have cold-air intake,I flashed the car with a 93 Octane performance tune and now I have Flowmaster mufflers. My 2008 Mustang GT is even more fun to drive.


    Year: 2008 Submodel: GT

    Helpful (5)

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