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Flowmaster American Thunder Axle-Back Exhaust (05-10 GT, GT500)

Market Price $655.99 You Save 13% ($86.02)
Our Price

$569.97

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  • Item 18417
  • MPN# 817460

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Features, Video & Details

  • Aggressive Flowmaster Super 44 Series Sound
  • Polished Stainless Steel 4" Tips
  • Durable Stainless Steel Construction
  • Includes Two Flowmaster Mufflers
  • Fits 2005-2010 GT, Bullitt and Shelby GT500

Review & Installation Video

Review & Install Video

I’m Justin with AmericanMuscle.com and I’m taking a closer look at Flowmaster’s American Thunder Classic Axle-back exhaust for the 2005-2010 Mustang GT. The classic incorporates the tried and true 40 series muffler, which is the muffler that started it all for Flowmaster many years ago. Now this sound defined Flowmaster and is one of the more aggressive exhausts you can get from their lineup. The classic just like the standard American Thunder incorporates that same 16-gauge aluminized steel for its ability to resist corrosion and its overall durability. Now just like the American Thunder standard, the classic also features that very cool black finish for a stealthy look, however features a slightly larger 4” stainless tip embossed with that very cool Flowmaster logo. Getting the classic bolted up to your Mustang is a very straightforward task, and should take you only about an hour using basic hand tools. Now let’s hear how Flowmaster’s American Thunder Classic sounds compared to your factory exhaust.

Classic Flowmaster Sound. Give your Mustang that unmistakeable Flowmaster sound with a nice power boost with the American Thunder Axle-Back Exhaust System. This Axle-Back 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 2.5" 16 gauge stainless steel tubing for its resistance to corrosion, the Flowmaster axle back features two special 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.

Application. This Flowmaster American Thunder Axle-Back Exhaust System is designed to fit the 2005-2010 Mustangs including the GT, Bullitt and Shelby GT500 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
  • (2) Muffler assemblies
  • (2) Clamps
Installation Info
Tech Specs
Axle-Back Exhaust Specifications
Piping Material: Stainless Steel Tip Material : Polished Stainless Steel
Piping Size: 2.5" Tip Size: 4"
Muffler Type: Chambered Fitment: 2005-2010 GT, Bullitt & GT500
Will it fit my Mustang?
  • Bullitt - 08, 09
  • GT - 05, 06, 07, 08, 09, 10
  • GT500 - 07, 08, 09, 10

People Who Bought This Item Also Bought

Most Helpful Reviews

5/5
sounds great

Gives it that great rumble and awesome tone. Great price for the product. Will be coming back for more.

Helpful (2)

5/5
Sounds Tuff

Good deep sound. Waiting for mufflers to burn out a little and get louder.

Helpful (1)

Overall Rating 4.7 out of 5 stars
Read All 40 Reviews

Customer Photos (10) Submit Your Photo

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5 Questions / 5 Answers

Ask a Question

Does this exhaust fit with the Roush Rear Valance

Eric

what if you have 3" exhaust coming from headers, do they come in 3" or just 2 a half inch?

gtbob

  • If your exhaust is 3" but the axle-back exhaust is 2.5" you will need to have it clamped down properly. However I would suggest purchasing an exhaust where the pipe size is 3" because you can be subjected to exhaust leaks or back pressure.

    KevinD92

Helpful (0)

does this exhaust sound good on an automatic

moto89

  • Yes it sure does!

    Bill

Helpful (0)

How much HP gain will I get with this axle-back exhaust if I already have a BAMA Tune and K&N Air Intake? Also, is this one of the best axle-back exhaust in terms of HP gain?

Wknichols13

  • You really will not see any gain in horsepower with any axleback setup. There is not enough back pressure built up at that point in the exhaust to affect your performance. Axle back exhausts are strictly for sound purposes. For performance you will want to look into headers and a mid pipe.

    SalC7

Helpful (0)

exhaust So i have a X pipe daul exhaust on my 2008 v6 and i was wandering if i could put the flow master classic thunder gt mufflers on it?

trouble

  • It might take a little hammering and bending but as long as the pipe diameters match up, then you should be fine. You might also have to hang your own brackets for the exhaust hangers though.

    Logan50

Show 1 more answer Helpful (0)

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Customer Reviews (40) Write a Review

Overall Rating 4.7

out of 5 stars

Installation Time:Afternoon

Installation Cost:0-$100

  • Loudness / Volume 4.470588 4.5
  • Exhaust Note 4.705883 4.7
  • Fit & Finish 4.323529 4.3
  • Bang For Your Buck 4.235294 4.2



  • 5/5

    Installation Time: Afternoon

    June 01, 2017

    Sounds Tuff

    Good deep sound. Waiting for mufflers to burn out a little and get louder.

    DonovanW

    Year: 2005 Submodel: GT

    Helpful (1)

  • 5/5

    Installation Time: Less than 1 Hour

    April 07, 2017

    Flowmaster AT

    I've had this same axle-back exhaust on three different Mustangs, and they sound great on all. Installation is simple, and the difference is amazing. Only issue I've had is the dreaded drone around 2K rpm. Other than that, they sound great.

    TripleYellowGT

    Year: 2008 Submodel: GT

    Helpful (1)

  • 5/5

    Installation Time: Less than 1 Hour

    October 28, 2016

    Flowmasters

    I'll start by saying these flowmasters have an awesome sound. Deep and mean sounding! The kit now includes super 44s vs the classic 40 series mufflers. I was after that classic hollow metallic fox body mustang flowmaster sound and the super 44s just aren't what I'm looking for. They sound more modern with a hint of the classic sound. Drone isn't too bad. Can still talk and hear the radio without issue. Quality is amazing. Look and feel like a great product. Easy install. I still give them a 5 star because they sound great and high quality. I was after a very specific sound and this didn't hit exactly what I wanted but if I hadn't gone in looking for something so specific I would be in love with these. I would say these have a modern mustang, camero, vette, challenger sound to them vs classic fox body.

    MrMustang

    Year: 2007 Submodel: GT

    Helpful (1)

  • 4/5

    Installation Time: Less than 1 Hour

    October 27, 2016

    Love the sound!

    This axle back gives the car a very deep, aggressive tone and sounds great with hot rod cams. That being said, since it has such a deep note, there's a lot of drone at 1500-1900 especially in 5th gear with 3.31 gears. And the exhaust isn't that loud at high RPM either, but that's on a car with stock cats and manifolds. Overall its a good quality, good sounding chambered exhaust. No issues with fitment and the tips look great.

    VaporStang

    Year: 2008 Submodel: GT

    Helpful (1)

  • 5/5

    July 23, 2016

    Great sound, bad packaging

    I received my exhaust on time and in a big box. When I opened it up the exhaust seemed to be in good condition, but the clamp to attach it the the pipes was bent as if it had been crushed. I ended up having to straighten then the clamp because I couldn't use the oem one since it was welded to the other muffler. Took longer than it should because of careless handling. Otherwise the sound is great and at 2k RPM it is amazing.

    Cody

    Year: 2010 Submodel: GT

    Helpful (1)

  • 5/5

    July 15, 2016

    Great upgrade to 05 GT

    Great sound and one of the best mods you can do yourself in under two hours. Great perfomance gains. Not to loud like other have said. American Muscle is the best they are spot on in descriptions and videos. I am running an 05 GT with Air Aid cold air intake, new Flowmasters and Bama performance custom tune. Great buy! worth the money..

    DREW

    Year: 2005 Submodel: GT

    Helpful (1)

  • 5/5

    Installation Time: Less than 1 Hour

    June 24, 2016

    Simple upgrade to enhance the tone of any Stang

    With simple hand tools, this install took me about an hour to complete. Easy bolt-on...excellent fit...and very nice exhaust tome as a result. Highly recommended.

    Locogeronimo

    Year: 2008 Submodel: GT500

    Helpful (1)

  • 5/5

    Installation Time: Afternoon

    May 11, 2016

    American Thunder Classic

    Love this exhaust, sounds great with great volume. Only problem i had with it was that I have Pypes' Dual Exhaust Conversion Kit for V6 Mustangs and since the products are from different companies, the metal hangers coming off the muffler are a little short and therefore it was very hard to make the mufflers line up and mine are kind of touching my bumper too so im a little worried about it melting

    Bill

    Year: 2009 Submodel: V6

    Helpful (1)

  • 5/5

    Installation Time: Afternoon

    August 18, 2015

    The Drone Goes Away

    Installing these wasn't as bad as I thought it was going to be. One of the hangers bolts just happened to be in between the frame and the muffler on the left side so there was only an inch or two of room to fit a wrench in. (I cursed myself for not purchasing ratchet wrenches) I have a 2008 Mustang GT so I'm not sure if this is the case on other year models but one of my exhaust hanger brackets had some sort of metal bracket welded to it that none of the others had, along with an extra bolt to hold it up there. So word of advice, don't go pulling on the old muffler until you have undone that "hidden" bolt or else you will bend that hanger. After that it was smooth sailing, the Flowmasters lined up very well on the first try and I didn't have to go back and mess with the alignment. The big moment when you crawl out from under there and jump into the drivers seat to turn it over for the first time was very memorable for me. Instant smile. These Flowmasters sound fantastic, they have a low booming tone in the lower RPMs but man when you get up to the high end the thing screams! I find myself leaving the door open when I start the car up now just to hear them as well as driving with the windows down. There was a definite drone around 55mph in 5th gear for me, VERY loud and deafening. It has gone away now that I have driven with them on my car for about a month, thank god.

    Zakk

    Year: 2008 Submodel: GT Kentucky

    Helpful (1)

  • 5/5

    Installation Time: Afternoon

    July 17, 2014

    The sound is amazing!

    I listened to many--many audio clips. You will not be disappointed. A full and deep tone and the neighbors won't hate you. Some drone between 60 and 70 mph but it's not bad and disappears over 70. After removing the old muffler, loosen the forward bracket on the drivers side and tighten after installation. This step would have saved us a lot of time. I am extremely happy with this purchase for my 2010 GT.

    KCPony77

    Year: 2010 Submodel: GT Olathe, KS, USA

    Helpful (1)

  • 5/5

    Installation Time: Less than 1 Hour

    April 13, 2014

    Great Exhaust

    Exhaust sounds great. Install is extremely easy once the factory exhaust has been removed. Highly recommend this product!

    Bquart

    Year: 2010 Submodel: GT Joplin, MO, USA

    Helpful (1)

  • 3/5

    Installation Time: Afternoon

    July 28, 2013

    dissappointed with fit

    Went on quickly, the time was spent trying to make everything look even and spaced right. Never did get it to look as balanced and evenly spaced as original, guess I'll off to the muffler shop.

    greg98tj

    Year: 2007 Submodel: GT seattle

    Helpful (1)

  • 3/5

    Installation Time: Afternoon

    May 27, 2013

    Overly expensive for what you get

    First off: - DRONE! On the throttle between 1500 and 2000 RPMs, and they drone significantly. Secondly, one of the tips was welded on slightly crooked. I expected a better fit and finish for an exhaust so expensive. They sound great when they aren't droning. Loud, but not "tick off the neighbors" loud. All in all I would not purchase them again - you can get just as good or better for less.

    mav100

    Year: 2008 Submodel: GT New York

    Helpful (1)

  • 4/5

    Installation Time: Afternoon

    April 26, 2013

    Great Sound but fit is a problem

    I received my Flowmasters in a very timely manner and couldn't wait to get them on. Not being a wrench turner, I was sure of the difficulty but the old ones came off and the new ones when one with much problem. The sound is great, with a bass that you can feel from 10' away. My only problem has been the alienment of the tips. The passenger side is perfect, but the drivers side I simply can't get to line up right. I've loosened the clamps at the H-pipe and all, but it looks like I'll need to renotch it and perhaps bend the hangers a bit. When I was parked, a late 70 year old gentleman walked by, scoped me out and said "sounds good." Not sure what else there is to say. I'll figure out the alienment yet. A good buy.

    Kipster

    Year: 2008 Submodel: GT Woodland Park, CO

    Helpful (1)

  • 5/5

    Installation Time: Afternoon

    December 29, 2012

    flowmaster classic axle back

    My 2010 GT sounds awesome .A lot of good compliments on sound, flowmasters look really good with 4" tips.highly recomend this classic axle back for any model year mustang.

    loustang210

    Year: 2010 Submodel: GT Lantana, FL, USA

    Helpful (1)

  • 5/5

    Installation Time: Shop Install

    Installation Cost: 0-$100

    October 18, 2012

    Flowmaster exhaust

    I am very happy with the flow master exhaust. Nice sound.

    Nancy80

    Year: 2005 Submodel: GT Fort Bragg, CA

    Helpful (1)

  • 4/5

    Installation Time: Afternoon

    September 13, 2012

    flowmaster fitment problems

    i had to point out to american muscle that this product does not have 4 1/2 in tips. the first set did not fit at all. they were replaced and the second set fit better but not perfect. flowmaster has some work to do there. sound great as advertised.

    BJ62

    Year: 2007 Submodel: GT Roanoke, VA, USA

    Helpful (1)

  • 5/5

    Installation Time: Less than 1 Hour

    September 12, 2012

    Flowmaster

    Easy install best sounding mufflers on the market wouldnt put any other muffler on cause nothing sounds like a flowmaster had another company on at first just didnt have that sound i wanted the first time i fired my 09 GT up with the flowmasters on and have been smiling ever since

    Krell1095

    Year: 2009 Submodel: GT Hellertown PA

    Helpful (1)

  • 5/5

    Installation Time: Less than 1 Hour

    July 19, 2012

    this product gives my 07 gt a true mussle car sound

    great sounding exhaust for the mustang gt. some tweaking required on exhaust hangers for proper clearence. there is a drone noise between 55mph and 65mph but overall good exhaust for the money

    chris65

    Year: 2007 Submodel: GT syracuse ny,usa

    Helpful (1)

  • 4/5

    Installation Time: Less than 1 Hour

    December 20, 2011

    Flowmaster 40 Series

    After listening to a friends GT with same muffler, I wanted one because it was nice and loud. I was surprised that it was no where near as loud, I guess cause he has a full exhaust (headers, off-road pipe). Not totally disappointed because it sounds a whole lot better (and a little louder) than stock mufflers.

    OneTrkPny

    Year: 2006 Submodel: GT Guam

    Helpful (1)

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