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2001-04 GM Silverado/Sierra 2500HD/3500HD 6.0L, 8.1L - American Thunder Exhaust 817328YouTube Button

Flowmaster American Thunder Cat-back Exhaust System

2001-2004 Chevrolet Silverado/GMC Sierra 2500/3500HD trucks with 6.0L or 8.1L engine. (See applications below)

PART# 817328

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$673.00   Suggested Retail
$604.95   Your Price
Estimated shipping date: 01/15/2021
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Aggressive sound


Finally, an exhaust system as durable and strong as the trucks it's designed to fit. Flowmaster® proudly introduces the American Thunder® cat-back exhaust system for 2001-2004 Chevy and GMC 2500HD/3500HD extended-cab and crew-cab trucks equipped with the 6.0 and 8.1L engines. Featuring dual 3.00-inch inlets and a single 3.5-inch mandrel-bent tailpipe thats finished off with a large 4.00-inch polished T304 stainless steel tip. This stainless steel system features a 50 Series Big Block® muffler gives your truck a deep moderately aggressive tone inside and out. Detailed step-by-step instructions and all necessary hardware are included to allow an easy, at-home installation. The system is covered by our Lifetime Limited Warranty.


  • 3.50-inch Mandrel-bent 16-gauge Stainless Steel Tubing
  • Includes Hangers and Hardware for an Easy Installation
  • Large 4.00-inch Polished 304 Stainless Steel Tip
  • Moderately Aggressive Exterior Exhaust Tone
  • Connects After Factory Catalytic Converter
  • Uses the Factory Hanger Locations
  • Quick and Easy Installation
  • Lifetime Limited Warranty


Emission Code5
Exhaust SeriesAmerican Thunder
Exit PositionSingle Side Exit
Heat ShieldNo
Inlet Diameter (in)3
Inlet PositionDual
Material409 Stainless Steel
Muffler Part NumberKit Only
Muffler Quantity1
Muffler Series50 Series Big Block
Outlet Diameter (in)3.5
Product TypeExhaust System
Single DualSingle
Sound LevelAggressive
System TypeCat-back
Tip Diameter (in)4
Tip Quantity1
Tubing Diameter (in)3.5
California Proposition 65 Chemical NameChromium (hexavalent compounds)
Nickel (Metallic)
California Proposition 65 RequiredYes
Part Number817328



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.

Tech Resources

Fits 2001-2004 Chevrolet Silverado and GMC Sierra 2500, 3500 3/4 Ton or 1 Ton HD chassis with 6.0L or 8.1L engine, fits Extended Cab and Crew Cab models.


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