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Flowmaster Force II Cat-Back Exhaust (99-04 GT, Mach 1)

AmericanMuscle no longer carries the Flowmaster Force II Cat-Back Exhaust (99-04 GT, Mach 1). Please check out 1999-2004 Mustang Cat-Back Exhaust for an updated selection.
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AmericanMuscle no longer carries the Flowmaster Force II Cat-Back Exhaust (99-04 GT, Mach 1). Please check out 1999-2004 Mustang Cat-Back Exhaust for an updated selection.

Features, Video & Details

  • Classic Flowmaster 50 Series Sound
  • Durable Aluminized Steel Construction
  • 2.5" Mandrel-Bent Tubing
  • 3" Polished Stainless Steel Tips
  • Includes Two Flowmaster 50 Series Mufflers
  • Fits 1999 to 2004 GT, Mach 1, and Bullitt Mustangs

Review & Installation Video

Review & Install Video

Hi I’m Justin with, and I’m breaking down Flowmaster’s Force II series catback exhaust, fitting the 99-04 Mustang GT and Mach 1. What makes this kit different to Flowmaster’s American Thunder is the mufflers. The Force II centers around their classic 50’s series mufflers, which is great for someone who enjoys that iconic Flowmaster sound, but without being too loud. This system features 2.5” mandrel bent aluminized steel tubing which Flowmaster enjoys using with a lot of their kits. That aluminized steel is going to be very durable, it’s going to resist corrosion well, it’s also going to help keep the cost down versus more expensive stainless steel. Besides the mandrel bent tubing, we also have the 50 series mufflers, all exiting out these 3” hand polished OE style tips. Since Ford chose to weld the factory exhaust on these cars, you will need to cut it off in order to get started with the install. Once you have that out of the way, getting the Force II installed is a pretty straightforward task, that should take you about 2 hours using basic hand tools. Now let’s hear how Flowmaster’s Force II sounds compared to our factory exhaust.

Signature Flowmaster Sound. Give your Mustang that unmistakeable Flowmaster sound with the Force II Cat-Back Exhaust system from AmericanMuscle. The Flowmaster Force II Cat-Back Exhaust with its mandrel bent tubing will greatly improve your Mustangs exhaust flow for an increase in power, and the included 50 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 Force II Cat-Back features two 50 Series chambered mufflers with 3.0" diameter OEM style polished stainless steel tips for great muscle car looks and sound.

Application. This Flowmaster Force II Cat-Back exhaust system is specifically designed to fit the 1999 to 2004 GT, 2001 Bullitt, and 2003 to 2004 Mach 1 Mustangs for both impressive looks and sound. This system will not fit the SVT Cobra models.
What's in the Box
  • (2) Muffler assemblies/li>
  • (2) Over axle pipes
  • (2) Exhaust Tips
  • (2) Clamps
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

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Customer Reviews (7) Write a Review

Overall Rating 4.1

out of 5 stars

Installation Time:Afternoon

Installation Cost:$100-$250

  • Loudness / Volume 4 4
  • Exhaust Note 4.714286 4.7
  • Fit & Finish 4.142857 4.1
  • Bang For Your Buck 4.285714 4.3

  • 4/5

    Installation Time: Afternoon

    May 03, 2018

    A little disappointed

    I do agree this a great system sounds great but I am very disappointed in the fact that after two weeks of having the exhaust on the tailpipes are already starting to rust I would think for the amount of money we pay for the system the product will be a little bit better


    Year: 2000 Submodel: GT

    Helpful (2)

  • 5/5

    Installation Time: Shop Install

    Installation Cost: $100-$250

    March 24, 2016

    Deep and Loud

    I have had this catback on my car for 7years now and everyone is amazed how deep and loud it is. But this is when fitted with a O/R mid pipe. I have an O/R bassani X and with the catback I have no rasp. And at ideal its louder than my friends 40 Series with O/R pypes X. But I will say it drones at certain RPMs. But the deep rumble makes up for it. I'm about to switch to an H-pipe to get an even deeper rumble from it.


    Year: 2001 Submodel: Bullitt

    Helpful (3)

  • 3/5

    Installation Time: Afternoon

    February 24, 2015

    long term update

    Great fit and sound, but does not hold up long term. A baffle came loose in one of the mufflers after 3 years (rattles) and a pipe rusted through at the H pipe joint at 6.5 years. This is with full time use in Kansas weather.


    Year: 2001 Submodel: GT Ottawa ks

    Helpful (4)

  • 5/5

    Installation Time: Afternoon

    June 12, 2012

    Force II on 2002 Mustang GT

    This exhaust was a great choice! If you're looking for an exhaust that isn't too loud but still has a great deep tone, this is the one for you! It isn't too loud where it scares people but it's enough to make people turn their heads! Great product!


    Year: 2002 Submodel: GT Richmond, VA, USA

    Helpful (4)

  • 4/5

    Installation Time: Afternoon

    May 26, 2012

    Gives your V6 a deep sound

    I have installed this along with BBK Headers and off-road pypes x-pipe and with these 50 series give my 3.8 a nice deep tone that i love. Fitment...take some elbow grease to get it fit nice, i had the back exhaust slightly touching my axle but not too big of a deal. Real great product, good shipping and good quality. I would deff buy this again. The tips look great out the back and the sound is deff a head turner. Thank AM!


    Year: 2000 Submodel: V6 Cicero, NY

    Helpful (5)

  • 4/5

    Installation Time: Afternoon

    April 27, 2012

    A great product for an amazing price.

    This exhaust was a perfect fit for my '02 GT. I jacked the car up and was still able to install it with no difficulties. It looks great ad sounds nice a throaty, just like a mustang should. It isn't very loud so you can actually hear other things inside the car, but is still loud enough to stand out from others.


    Year: 2002 Submodel: GT Milford, PA 18337, USA

    Helpful (4)

  • 4/5

    Installation Time: Less than 1 Hour

    January 27, 2012

    Mach 1

    I have a 03 Mach 1 and the stock exhaust is awesome but I wanted more power and sound so I went with flowmaster and it payed off!


    Year: 2003 Submodel: Mach 1 Andover ks

    Helpful (3)

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