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Flowmaster American Thunder Cat-Back Exhaust (99-04 GT, Mach 1)

100+ Reviews
Our Price

$481.97

  • Item #18410
  • MPN# 17312

  • Market Price $544.63
  • You Save 12% ($62.66)
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Product Videos Customer Photos
Features
  • Aggressive Flowmaster Sound.
  • Super 40 Series Mufflers.
  • 3" Polished Stainless Steel Tips.
  • Mandrel-Bent Tubing.
  • Durable Aluminized Steel Construction.
  • Fits 1999-2004 GT, Mach 1, and Bullitt Mustangs.
Description
Flowmaster Sound.The Flowmaster American Thunder Cat-Back exhaust system with its mandrel bent tubing will greatly improve your 1999 to 2004 Mustangs exhaust flow for an increase in power, and their included Super 40 Series Mufflers will improve your exhausts sound for a deeper throatier muscle car exhaust note.

Quality Construction. Constructed from mandrel bent 2.5" 16 gauge aluminized steel tubing for it's corrosion resistant properties the Flowmaster American Thunder Cat-Back features their Super 40 Series chambered mufflers with 3.0 " diameter OEM style polished stainless steel tips for great muscle car looks and sound.

Fitment. This Flowmaster American Thunder Cat-Back exhaust system is specifically designed to fit the 1999-2004 GT, 2001 Bullitt, and 2003-2004 Mach 1 Mustangs for both impressive looks and sound. This system will not fit the SVT Cobra Mustangs.

Fitment: 1999 2000 2001 2002 2003 2004 Details

What's in the Box
  • (1) Right muffler assembly
  • (1) Left muffler assembly
  • (1) Right tailpipe assembly
  • (1) Left tailpipe assembly
  • (2) Clamps
  • (4) Lock Washers
Installation Info
Tech Specs
Cat-Back Exhaust Specifications
Piping Material: Aluminized Steel Tip Material : Polished Stainless Steel
Piping Size: 2.5" Tip Size: 3.0"
Muffler Type: Chambered Fitment: 1999-2004 GT, Bullitt and Mach 1 Mustangs
Will it fit my Mustang?
  • Bullitt - 01
  • Mach 1 - 03, 04
  • GT - 99, 00, 01, 02, 03, 04

Fits GT, Mach 1, and Bullitt

Most Helpful Reviews

5/5
Great sound

I had the magnapacks but decided to go with the flowmaster cat back. I feel that flowmasters make the best sounding exhaust for any mustang. Love the color black, installed with no problems. Thanks am ...

Read More
Helpful (2)

5/5
v6 mustang

Very very happy with this exhaust, I first got the mac O/R H with SLP loudmouth 1 exhaust...big mistake, it was way too loud, and not a good loud. switch to this exhaust and it sounds perfect. good and ...

Read More
Helpful (75)

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

Hi I’m Justin with AmericanMuscle.com, and I’m breaking down Flowmaster’s American thunder Cat-Back exhaust fitting the 99-04 Mustang GT and Mach 1. A few of the big points with this catback are the 2.5” aluminized steel mandrel bent tubing, the 3” brightly polished OE style tips, and finally and most importantly, Flowmaster’s super 40 series mufflers which give this kit its very aggressive and unique sound. Flowmaster does offer a full stainless version of this same exact exhaust, which will be slightly lighter and better at resisting corrosion, however it does come with a slightly higher price tag. Due to the design of the factory exhaust you will need to cut it off in sections using a saw or something similar. Once you get that out of the way, the American Thunder bolts directly to your factory Mid Pipe, in about 2 hours using some basic hand tools and the included clamps. Now let’s hear how Flowmaster’s American Thunder sounds compared to our factory exhaust.

Customer Photos (22) View All Photos

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14 Questions / 7 Answers

Ask a Question

I am able to exhange the mufflers for the Super 44s without any customizations?

quin

  • I hope this helps...depending on your size of pipes (I orginally had 2 1/4 in pipes, and ordered 2 1/2 in mufflers), usually if you take to a perfessional shop they can install sleeves or inserts to match the pipes installed currently. But, if you are going to install 2 1/2 in muffs; go for the kit that has the same size pipes from the cats down. (Should have learned this from the first opprotunity around. ) Match to match in muffs and pipes saves alot of time down the line.

    SweetWilly81

    Good Answer (0) (0)

Answer This Question I need this answered (0) (0)

will this fit stock pipes or am i going to have to aftermarket pipes along with this?

Codyjdaniel

  • This American Thunder Catback will bolt up to your factory mid-pipe without any problems! This catback would also bolt up to an aftermarket mid-pipe if you wished to do that at a later time. Hope this helps!

    LisaS

    Good Answer (6) (0)

Show 3 more answers Question Resolved

Do I have to buy the Pypes hanger kit if I have a v6? I have the v6 bumper right now, but plan on getting a GT one later down the road. Will this exhaust be adjustable without the hanger kit?

Luk3

  • When I got my dual exhaust conversion my mechanic had said it wasn't neccesary; however, it is recommended especially if you wish to have a secure installation and it makes it a whole lot easier for you or whoever is doing the installation. On the bumper note I was able to make a few measurements and made a cut onto the bumper it's definitely cheaper than buying a new bumper any bodyshop could do it cheap and most likely the muffler shop will have what's needed for the cutting.

    Dvorak33

    Good Answer (0) (0)

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Customer Reviews (100+) Write a Review

Overall Rating 4.7

out of 5 stars




  • 5/5

    August 04, 2011

    Great sound

    I had the magnapacks but decided to go with the flowmaster cat back. I feel that flowmasters make the best sounding exhaust for any mustang. Love the color black, installed with no problems. Thanks am for another great service.

    Anthony E

    Year: 2002 Model: GT Driving Style: Daily Driver

    Helpful (2) (0)

  • 5/5

    January 10, 2010

    v6 mustang

    Very very happy with this exhaust, I first got the mac O/R H with SLP loudmouth 1 exhaust...big mistake, it was way too loud, and not a good loud. switch to this exhaust and it sounds perfect. good and deep, not raspy and not a tuner sound. I would recomend this for ANY v6 stang looking for duels.

    Jeremy

    Helpful (75) (8)

  • 5/5

    March 12, 2010

    American Thunder

    Just had this installed on my 2003 Mustang GT Convertible, this was exactly the sound I was going for. If you're like me, and don't want your car to sound ridiculous like some exhausts, then this is the one for you. I previously had Borla Stingers installed for about 15 minutes, and it was just stupid loud, didn't even sound cool to me, just stupid loud. This exhaust is one of the best I have heard, because I just wanted something louder than stock, but not obnoxiously loud. When you get on it it sounds great, but also sounds great just cruising, but you can put it up in a higher gear and it will get quieter, and there is some drone on the highway, but nothing too bad. I can't believe people actually like straight-through pipes, it would just be a constant drone, and annoying sound all of the time. I would highly recommend this exhaust, and I got the Stainless Steal version, great fitment, and a great quality product unlike others.

    Sean

    Year: 2003 Model: GT

    Helpful (29) (3)

  • 5/5

    January 22, 2010

    great sound

    This is a great sounding exhaust not overpowering loud but just loud enough. Sounds great when you get on it.

    Dragan00

    Helpful (14) (1)

  • 5/5

    Installation Time: Afternoon

    October 26, 2011

    True muscle car sound like no other!

    The American Thunder catback exhaust system is an easy bolt on kit that adds substantially more horsepower and an engine tone that is truly amazing. Installation is very simple, with only four bolts and a few exhaust hangers to deal with, meaning this mod will only take an hour or two. The result of the less restrictive 2.5" pipes (compared to stock 2.25") combined with a pair of Flowmaster Super 40 mufflers and 3" chrome exhaust tips is a sound that will turn heads! The deep, muscle car growl produced by this kit is loud enough to please any car enthusiast but not so loud that they annoy others on the road. The Flowmaster American Thunder catback exhaust system adds an excellent amount of horsepower and a sound that will draw a lot of attention to your Mustang with as little as a few hours labor and the use of common hand tools. A must have for anyone who wants to add a little more muscle to their muscle car!

    LanceH

    Year: 2004 Model: GT Driving Style: Daily Driver 'Stangs I have owned: 1 Mobile, Alabama

    Helpful (23) (6)

  • 5/5

    June 29, 2010

    WOW!!!

    wow i got this system at 10 in the mornin, stalled a little then finally started assembling it at 3pm and was done by 7! wouldve been done at 5 if i didnt have to take the mufflers back off and drill some of the hole out on the right muffler connecter! overall im more then happy with this exhaust, its amazing and i would reccomend this to anybody that likes a nice smooth, deep tone but not overly loud car!

    kellen

    Helpful (12) (1)

  • 5/5

    January 18, 2011

    more that satisfied

    Just installed on my 2000 vert gt, more than happy with the low rumble and subtle backfire, noticable slight gain in power (untuned) in mid rpm range. Could be a tad louder, can easily be fixed with a midpipe.

    Pat

    Year: 2000 Model: GT Driving Style: Daily Driver

    Helpful (9) (2)

  • 5/5

    May 01, 2011

    satisfied

    The only thing that I am disturbed with this product, is they do not come with bolts to connect the joints. So when you take off the stock exhaust and your bolts break because of rusting you will be going to the nearest hardware shop.

    Brandon Morris

    Year: 2004 Model: V6 Driving Style: Daily Driver

    Helpful (6) (1)

  • 5/5

    Installation Time: Afternoon

    December 15, 2011

    Sound Great in the V6

    i have a 00 V6, and wanted to get some muscle car tone out of her. I took a chance and bought the pace setter h pipe and these bad boys... I was shocked with the upgrade in take off and sound.. My V6 doesn't sound like a V8 would with a full exhaust, but if deff sounds like a muscle car. Much better than i expected.. deep tone, and pretty throaty.. nothing like a ricer, so any V6 owner looking for an upgrade.. here is the answer to all your problems.

    Carlino

    Year: 2000 Model: V6 Driving Style: Daily Driver 'Stangs I have owned: 1 CT

    Helpful (4) (0)

  • 5/5

    January 18, 2011

    Sounds great!!

    This is the perfect exhaust if you're looking for a nice deep rumble! Sounds great inside and out. Took less than 1 hour to install without any problems at all. Very happy with this purchase and would recomend to anyone looking to get more noise out of their stock v8!

    Anthony

    Helpful (4) (0)

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