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Flowmaster American Thunder Crossmember-Back Exhaust System

1967-1974 Chevrolet Camaro, Pontiac Firebird with V8 engine. 2.50 inch Stainless Steel

Part # 817104 Be the first to write a review
Estimated shipping date: 04/04/2022
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Flowmaster® is proud to introduce our American Thunder® dual exhaust system for 1967-1974 Chevrolet Camaro, Pontiac Firebird and 1968-1974 Chevrolet Nova's. This all stainless steel exhaust system features our exclusive design 80 Series™ Crossflow muffler, all mandrel-bent dual 2.50-inch pipes including an H-pipe crossover for a deep smooth tone that also minimizes any back-rap on deceleration. The dual 2.50-inch stainless steel tailpipes provide a deep rich sound and optimum performance. This crossmember-back 409S stainless system gives these classic muscle cars a moderate tone inside and out. Using the crossflow design, this exhaust places the muffler in the factory location behind the rear axle retaining full ground clearance under the car while offering all the performance benefits of a full dual exhaust system. The system includes all parts, hardware and illustrated instructions, and like all Flowmaster stainless steel street products, it includes our Limited Lifetime Warranty.


  • H-pipe Crossover for Maximum Power and Deep Tone
  • Includes Hangers and Hardware for Easy Installation
  • 80 Series Cross-flow Performance Muffler
  • Mandrel-bent Stainless Steel Tubing
  • Moderate Exterior Exhaust Tone
  • Maximum Ground Clearance
  • Stainless Steel Construction
  • Lifetime Limited Warranty
  • Crossmember-back System

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
Heat ShieldNo
Inlet Diameter (in)2.5
Material409 Stainless Steel
Muffler Part NumberKit Only
Muffler Quantity1
Muffler Series80 Series Crossflow
Outlet Diameter (in)2.5
Product TypeExhaust System
Single DualDual
Sound LevelModerate
System TypeCrossmember-back
Tip QuantityNot Included
Tube Diameter2.5 inch
Tubing Diameter (in)2.5
Type of ExhaustCrossmember-back
California Proposition 65 Chemical NameChromium (hexavalent compounds)
Nickel (Metallic)
California Proposition 65 RequiredYes
Part Number817104

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.

Convertible models require 3/8-inch of shims on the factory X-brace for clearance of the exhaust tubing. Connectors for factory manifolds or headers not included.

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    *Free Shipping & Handling only offered to the contiguous US on orders over $100, excludes clearance parts and oversized packages.

    Some parts are not legal for use in California or other states with similar regulations.