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Flowmaster American Thunder Cat-back Exhaust System

1998-2003 Ford F-150 with 4.6L or 5.4L engine. Fits both 2/4-wheel drive models.

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Flowmaster's American Thunder cat-back exhaust system for the 1998-2003 Ford F-150 pickup truck is perfect for the person looking for an aggressive exterior sound level with all of the performance benefits that you would expect from Flowmaster. This system allows you the choice of either dual out the rear exit tailpipes, or dual out the sides behind the rear wheels, which is perfect for towing. The bolt-on 409S stainless steel system fits both the 4.6L and the 5.4L V8 engines and features a Super 40 Series performance muffler and dual 2.50-inch mandrel-bent tailpipes finished off with a pair of large 3.50-inch polished stainless steel tips. This system is designed to fit all 2/4 wheel drives, all wheelbases and is covered by our Lifetime Limited Warranty. Designed for an easy fit, this system includes all necessary parts and hardware for installation.


  • Large 3.50-inch Polished 304 Stainless Steel Tips
  • Dual Outlet Super 40 Series Performance Muffler
  • Mandrel-bent Stainless Steel Construction
  • Aggressive Exterior Performance Tone
  • Uses the Factory Hanger Locations
  • Multiple Exit Styles Provided in Kit
  • Clears the Factory Spare Tire
  • Lifetime Limited Warranty
  • Moderate Interior Tone
  • Easy Installation

About Flowmaster

Flowmaster® is a household name, and for good reason. They've built legendary exhaust systems and mufflers for decades, and now offer performance air intakes, catalytic converters, and headers to give your hot rod performance to match the iconic Flowmaster sound.

Brand Flowmaster
Emission Code5
Exhaust SeriesAmerican Thunder
Exit PositionDual Out Rear / Dual Out Side
Heat ShieldNo
Inlet Diameter (in)2.5
Material409 Stainless Steel
Muffler Part NumberKit Only
Muffler Quantity1
Muffler SeriesSuper 40 Series
Outlet Diameter (in)2.5
Product TypeExhaust System
Single DualDual
Sound LevelAggressive
System TypeCat-back
Tip Diameter (in)3.5
Tip Length (in)13
Tip Quantity2
Tubing Diameter (in)2.5
California Proposition 65 Chemical NameChromium (hexavalent compounds)
Nickel (Metallic)
California Proposition 65 RequiredYes
Part Number817663

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.

Fits 1998-2003 Ford F-150 with 4.6L or 5.4L engine. Fits both 2/4-wheel drive models.

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