Description
Overview
The Flowmaster American Thunder Crossmember-Back Exhaust System is a purpose-built dual exhaust upgrade engineered specifically for 1967-1972 Chevrolet and GMC 4WD trucks, including the K10, K15/K1500, K20, and K25/K2500 with V8 power. Designed for the enthusiast who wants their classic Chevy or GMC pickup to look and sound the part, this crossmember-back system delivers an aggressive-to-moderate tone both inside and outside the cab, striking a balance between muscle and drivability.
Starting at the crossmember and running back, the system arrives complete with a built-in H-pipe crossover that improves exhaust scavenging for smoother, more efficient flow. Every section is constructed from mandrel-bent 2.50-inch stainless steel tubing to maintain consistent diameter through each bend, and the silver piping is paired with two black Super 44 Series performance mufflers for that signature Flowmaster growl.
Key Benefits
The Super 44 mufflers are the heart of this dual setup, delivering a deep, aggressive sound with a moderate character that won’t overpower the cabin. Each muffler measures 19.50 inches in overall length with an offset inlet and a 2.50-inch outlet, feeding a true dual tailpipe layout. Because the system is CARB (California) compliant with an Emission Code of 5, it’s a smart choice for owners who need to stay street-legal while chasing better sound and flow.
- Complete crossmember-back dual exhaust engineered for 1967-1972 Chevy/GMC K-series 4WD V8 trucks
- Mandrel-bent 2.50-inch stainless steel tubing in silver for durability and consistent flow
- Pair of black Super 44 Series performance mufflers (19.50-inch length, offset inlet, 2.50-inch outlet)
- Built-in H-pipe crossover for improved exhaust scavenging
- Aggressive-to-moderate interior and exterior sound level
- CARB compliant (Emission Code 5) and backed by a Lifetime Limited Warranty
Choose Your Tailpipe Exit
Personalize the fit and stance of your truck with three tailpipe exit configurations: a turndown behind the rear tires, a side exit behind the rear tires, or straight out the back under the bumper. Whatever look you’re after, there’s a routing option to match your build. Exhaust tips are sold separately, giving you the freedom to finish the system to your taste.
Fitment & Installation
This American Thunder system is designed for both short and long wheelbase 1967-1972 Chevrolet and GMC K10, K15/K1500, K20, and K25/K2500 4WD trucks equipped with a V8. It includes all new hangers and the hardware necessary for installation, so you have what you need to bolt it up. Please note the heat shield is not included, and the kit is offered as a muffler kit configuration. This product carries a California Proposition 65 warning. Backed by a Lifetime Limited Warranty, the American Thunder Crossmember-Back system is a proven way to add classic Flowmaster performance and sound to your vintage 4WD hauler.
