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

Market Price $992.99 You Save 13% ($130.02)
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  • Item 18427
  • MPN# 817494

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Features, Video & Details

  • Aggressive Flowmaster 60-Series Delta Flow Sound
  • Durable 409 Stainless Steel Construction
  • 3" Mandrel-Bent Tubing
  • 4" Polished Stainless Steel Tips
  • Includes Scavenger X-Pipe and Two Flowmaster 60 Series Mufflers
  • Fits 2005-2010 GT, Bullitt, and Shelby GT500

Review & Installation Video

Review & Install Video

Hey I’m Justin with and I’m taking a closer look at Flowmaster’s American Thunder series Cat-Back exhaust fitting the 2005-2010 Mustang GT, and GT 500. As you may or may not know, Flowmaster offers a wide variety of different mufflers, each with their own unique sound. In this case, the American Thunder centers around these two 60 series delta flow mufflers, which of course will still give you that iconic Flowmaster sound, but they’re not going to be as loud as Flowmaster’s 40 series mufflers. The American Thunder is constructed using durable 409 grade stainless steel, even including those 3 chambered 60 series mufflers. The system also features mandrel bends throughout, all exiting out these 4” polished tips, embossed with that Flowmaster logo. Getting this Cat-Back bolted up to your S197 is a very simple task, that should take you no more than 2 hours using basic hand tools. Now let’s hear how to Flowmaster American Thunder Cat-Back sounds compared to our factory exhaust.

Signature Flowmaster Sound. Give your Mustang that unmistakable Flowmaster sound with the American Thunder Cat-Back Exhaust system from AmericanMuscle. The Flowmaster American Thunder Cat-Back Exhaust with its mandrel bent tubing will greatly improve your Mustang's exhaust flow for an increase in power. The included 60 Series Delta Flow Mufflers will improve your exhaust's sound for a deep aggressive exhaust note.

Reuses Stock Cats. Installation of the Flowmaster American Thunder Cat-Back Exhaust requires cutting the factory H-Pipe to bolt up the new Scavenger X-Pipe directly behind the factory catalytic converters, making your Mustang 100% smog-legal.

Race Car Growl. The included Scavenger X-Pipe not only helps increase power, but it also adds a loud raspy, race car growl to the sound of your exhaust with its modern "X" crossover pipe design.

Quality Construction. Constructed from durable 3" 16 gauge 409 stainless steel tubing for it's corrosion resistant properties, the Flowmaster American Thunder Cat-Back features two 60 Series Delta Flow American Thunder mufflers with massive 4.0" diameter polished stainless steel tips for great muscle car looks and sound. As an added bonus, the tips are embossed with the "Flowmaster" logo for true custom styling.

Application. This Flowmaster American Thunder Cat-Back Exhaust System is designed to fit the 2005 to 2010 GT, Bullitt and the 2007-2010 Shelby GT500 Mustangs for both great looks and great sound.

Shipping Note: This product can not be shipped to an APO/FPO, Guam, or US Virgin Islands addresses.

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) Over axle pipes
  • (1) Scavenger X-pipe Assembly
  • (4) Clamps
Installation Info
Tech Specs
Cat-Back Exhaust Specifications
Piping Material: 409 Stainless Steel Tip Material : Polished Stainless Steel
Piping Size: 3.0" Tip Size: 4.0"
Muffler Type: Chambered Fitment: 2005-2010 GT, Bullitt and Shelby GT500
Will it fit my Mustang?
  • Bullitt - 08, 09
  • GT - 05, 06, 07, 08, 09, 10
  • GT500 - 07, 08, 09, 10

Most Helpful Reviews


For 750 dollars and for that unmistakeable flowmaster sound this exhaust needs to be deeper and louder at all rpms and idle. It is barely noticeable under normal driving conditions and only comes to life ...

Read More
Helpful (2)


I put on a a C&L Racer CAI and the Flowmaster and ohh my god what a difference! It sounds absolutely amazing! I swear there is a caged beast under the hood just trying to get out! On top of the amazing ...

Read More
Helpful (3)

Overall Rating 4.6 out of 5 stars
Read All 7 Reviews

Customer Photos (6) Submit Your Photo

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7 Questions / 9 Answers

Ask a Question

Hi, Will this fit my 06 GT with auto trans? I'm not sure if there is a different fit for auto and stick? Thanks, Ron


Helpful (0)
  • Yes, this kit will fit with both auto and manual transmissions.


Tubing Diameter? I have seen other information on this product that seems to suggests the tubing is 3" as opposed to 2.5". Can you confirm what the true diameter is?


Helpful (0)
  • Flowmaster American Thunder Catback Exhaust for (05-10) Mustang Gt/Shelby 500, Part # 817494 . Specs are 2.5 inches for inlet, 3.00 inches for outlet


Will this exhaust work with Mac shorty headers? Pretty much was wondering what else I'm going to need for it to bolt up to the header I have on it (Mac shortys)


Helpful (0)
  • You will not need anything else, this Flowmaster American Thunder Cat-Back Exhaust (05-10 GT, GT500) will bolt right up to your setup!


What headers would best work for American Thunder? I was looking to buy some Kook Long Tube Headers Full-Length Natural 1 5/8" Primaries 6801CV, but I'm a little hesitant about installing them with American Thunders due to the width of the Scavenger X-Pipe. Does it matter?


Helpful (0)
  • Either way this would not work due to this set up not having a shorty mid pipe required for the long tube headers.


what headers go good with this Im looking at some long tube headers, but i don't know which ones to get with this catback


Helpful (0)
  • I like the BBK Chrome tuned...the flowmasters are sick, I have it on my 06...the sound is incredible...


Show 1 more answer

Does this involve welding or does it bold and clamp to midpipe?


Helpful (0)
  • this includes a new X-pipe (mid-pipe) just fyi. But any exhaust cat-back can be held together with clamps but if you want better duability, sound, and performance you should atleast have all the connections mig or tig welded together.


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Customer Reviews (7) Write a Review

Overall Rating 4.6

out of 5 stars

Installation Time:Full Day

Installation Cost:$100-$250

  • Loudness / Volume 4.142857 4.1
  • Exhaust Note 4.428571 4.4
  • Fit & Finish 4.285714 4.3
  • Bang For Your Buck 4.428571 4.4

  • 2/5

    Installation Time: Shop Install

    Installation Cost: $100-$250

    November 22, 2013


    For 750 dollars and for that unmistakeable flowmaster sound this exhaust needs to be deeper and louder at all rpms and idle. It is barely noticeable under normal driving conditions and only comes to life under decent throttle, which sounds great, but only if you're getting on it a bit. Not enough character or sound through total driving range for the money and for the flowmaster tag.


    Year: 2006 Submodel: GT Austin, TX, USA

    Helpful (2)

  • 5/5

    Installation Time: Shop Install

    February 15, 2012


    I put on a a C&L Racer CAI and the Flowmaster and ohh my god what a difference! It sounds absolutely amazing! I swear there is a caged beast under the hood just trying to get out! On top of the amazing sound, it got rid of a droning noise I typically get in 5th gear at around 1700rpms. So not only did I gain an incredibly aggressive sound, I lost the annoying one in the process. Not to mention torque I got from the combination of the cat-back exhaust, the CAI and the Bama tune. Unbelievable!


    Year: 2009 Submodel: GT Marietta GA

    Helpful (3)

  • 5/5

    Installation Time: Less than 1 Hour

    October 16, 2015


    hands down for myself the best sounding and performing exaust on the market. have used them on all of my mustangs and quite a few other vehicles as well.


    Year: 2005 Submodel: GT us virgin islands

    Helpful (1)

  • 5/5

    Installation Time: Full Day

    April 26, 2012

    Great sound

    First have to say awsome delivery from AM came just in time when removing the old exhust/ recomend a lift when installing/ not as loud as I expected though but getting louder as it breaks in/ also recommend getting it tig welded to hold in in place/ minor knocks heard when going over harsh bumps/ sounds great not to loud but good rumble to get noticed


    Year: 2006 Submodel: GT New York

    Helpful (2)

  • 5/5

    Installation Time: Afternoon

    April 23, 2014

    Just Right

    I bought my car used and after being under it, I determined this is the exhaust the car has on it, so I decided to provide my two cents. If you are looking for a catback that'll wake your neighbors when you start the car and make children run and hide when you drive past the local school, this isn't the exhaust for you.However, this exhaust sounds incredible when you unleash some power. Don't get me wrong though, this exhaust still sounds impressive idling. It's quiet enough to not make your grandma mad when you pull up to Sunday dinner, but loud enough to really let other people know you're packing some serious horses under the hood.


    Year: 2007 Submodel: GT Cleveland, OH, USA

    Helpful (0)

  • 5/5

    Installation Time: Shop Install

    Installation Cost: 0-$100

    September 20, 2013

    Love this exhaust!

    I was going to go with a Borla Exhaust but decided on the Flowmaster. Im not disappointed at all on the choice I made. The flowmaster sounds awesome & looks great on my Mustang GT. Thanks American Muscle.


    Year: 2005 Submodel: GT China Spring, Tx

    Helpful (0)

  • 5/5

    Installation Time: Afternoon

    March 02, 2017

    Love them!

    Has great deep tone with bbk long tube headers and catted x pipe. Definitely would refer this to anyone who is looking for an exhuasted. Don't hesitate, just buy it. It's worth it.


    Year: 2006 Submodel: GT

    Helpful (0)

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