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Flowmaster American Thunder Crossmember-Back Exhaust System

Fits 1964-1966 Mustang, 2.50-inch stainless steel system.

Part # 817273 Be the first to write a review
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Delta Flow
This American Thunder® crossmember-back exhaust system is designed for all 1964-1966 Ford Mustang hardtop coupes with a V8 engine. The system features a free-flowing 2.50-inch mandrel-bent stainless steel H-pipe flowing into a pair of Super 44® Series mufflers for maximum power and that deep iconic sound. The 2.50-inch mandrel-bent stainless tailpipes tuck up high and are finished off with a pair of long 2.50-inch 304 stainless steel tips for that show car look. Includes all necessary parts, hardware and easy to follow instructions and is covered by our Lifetime Limited Warranty. Note: Does Not fit GT models or convertibles.


  • Includes Hangers and Hardware for an Easy Installation
  • Mandrel-bent 16-gauge Stainless Steel Tubing
  • Super 44 Series Performance Mufflers
  • Long Polished Stainless Steel Tips
  • Includes Built-in "H" Balance Pipe
  • Moderate Exterior Exhaust Tone
  • 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 Quantity2
Muffler Series40 Series Delta Flow
Outlet Diameter (in)2.5
Product TypeExhaust System
Single DualDual
Sound LevelAggressive / Moderate
System TypeCrossmember-back
Tip Diameter (in)2.5
Tip Quantity2
Tubing Diameter (in)2.5
California Proposition 65 Chemical NameChromium (hexavalent compounds)
Nickel (Metallic)
California Proposition 65 RequiredYes
Part Number817273

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.

Does not fit GT or convertible models.

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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.