For the person who is looking for a complete Cat-back dual exhaust system with an aggressive tone. With easy fit in mind, these systems are mandrel bent for maximum performance and include specially selected mufflers. American Thunder systems deliver a moderate to aggressive interior and exterior tone and are suited to the enthusiast who wants their performance to be heard. Like all Flowmaster systems, the benefits include improved throttle response, power and mileage. Designed for an easy fit, these systems include all necessary parts and hardware for easy installation.
Features:
- Premium Flowmaster Quality
- 3 Year Limited Warranty
- Made in the USA
- Mandrel Bent Tubing
- Includes Hangers And Hardware For Easy Installation
- Dyno Tuned for Maximum Performance
Holley Performance Emission Code 5: This part is legal for sale or use on Emissions Controlled Vehicles; Uncontrolled (Non-Emissions Controlled) Vehicles; and Racing Use Only Vehicles because it does not affect vehicle emissions and is not covered by emissions regulations
Installation Notes:
Fits 1999-2004 Ford Mustang GT, MACH1 and Bullitt with 4.6L SOHC engine. Does Not fit Cobra.

About Flowmaster
Manufacturer of performance exhaust systems, mufflers, performance air intakes, turbo boost modules, catalytic converters, race mufflers, headers and numerous exhaust accessories for late model cars, trucks, off-road, Jeeps, SUV’s, classic muscle cars, powersports vehicles and more. Flowmaster® gives you lots of exhaust choices with 12 designs of chambered mufflers, 3 styles of our exclusive “laminar-flow” mufflers and a new line of FlowFX “straight-through” performance mufflers, along with 5 sound categories of exhaust systems, giving you the customer, the power to custom tailor the sound of your vehicle whether you prefer mild, moderate or aggressive tones and sound levels. Since 1983, Flowmaster is the company you can trust, and has led the industry in offering only the best products you can buy for your vehicles.

Vehicle Fitment:
The Vehicle Fitment Guide is to be used as a general reference. The data has been provided by our suppliers and manufacturers and may contain errors or incorrect data. Always refer to a professional to verify correct fitment for your vehicle.
Make |
Model |
Submodel |
Years |
Engine |
Fitment Notes |
Ford |
Mustang |
GT Bullitt |
2001 |
4.6L / 281 / V8 |
Dual; Dual Rear Exit; Incl. 2.5 in. Tailpipes/Super 40 Series(TM) Mufflers/3.0 in. Stainless Tips; 409 Stainless Steel;50 State Legal / California Emissions Compliant |
Ford |
Mustang |
GT |
1999 |
4.6L / 281 / V8 |
Dual; Dual Rear Exit; Incl. 2.5 in. Tailpipes/Super 40 Series(TM) Mufflers/3.0 in. Stainless Tips; 409 Stainless Steel;50 State Legal / California Emissions Compliant |
Ford |
Mustang |
GT |
2000 |
4.6L / 281 / V8 |
Dual; Dual Rear Exit; Incl. 2.5 in. Tailpipes/Super 40 Series(TM) Mufflers/3.0 in. Stainless Tips; 409 Stainless Steel;50 State Legal / California Emissions Compliant |
Ford |
Mustang |
GT |
2001 |
4.6L / 281 / V8 |
Dual; Dual Rear Exit; Incl. 2.5 in. Tailpipes/Super 40 Series(TM) Mufflers/3.0 in. Stainless Tips; 409 Stainless Steel;50 State Legal / California Emissions Compliant |
Ford |
Mustang |
GT |
2002 |
4.6L / 281 / V8 |
Dual; Dual Rear Exit; Incl. 2.5 in. Tailpipes/Super 40 Series(TM) Mufflers/3.0 in. Stainless Tips; 409 Stainless Steel;50 State Legal / California Emissions Compliant |
Ford |
Mustang |
GT |
2003 |
4.6L / 281 / V8 |
Dual; Dual Rear Exit; Incl. 2.5 in. Tailpipes/Super 40 Series(TM) Mufflers/3.0 in. Stainless Tips; 409 Stainless Steel;50 State Legal / California Emissions Compliant |
Ford |
Mustang |
GT |
2004 |
4.6L / 281 / V8 |
Dual; Dual Rear Exit; Incl. 2.5 in. Tailpipes/Super 40 Series(TM) Mufflers/3.0 in. Stainless Tips; 409 Stainless Steel;50 State Legal / California Emissions Compliant |
Ford |
Mustang |
Mach 1 |
2003 |
4.6L / 281 / V8 |
Dual; Dual Rear Exit; Incl. 2.5 in. Tailpipes/Super 40 Series(TM) Mufflers/3.0 in. Stainless Tips; 409 Stainless Steel;50 State Legal / California Emissions Compliant |
Ford |
Mustang |
Mach 1 |
2004 |
4.6L / 281 / V8 |
Dual; Dual Rear Exit; Incl. 2.5 in. Tailpipes/Super 40 Series(TM) Mufflers/3.0 in. Stainless Tips; 409 Stainless Steel;50 State Legal / California Emissions Compliant |