68-91 GM Truck Headers 396/454

The 68-91 GM Truck Headers for 396/454 engines are an essential performance upgrade for classic and late-model Chevrolet truck owners seeking improved exhaust scavenging and horsepower gains. These headers replace restrictive factory cast-iron manifolds, allowing exhaust gases to exit more efficiently and freeing up power that modern trucks can deliver. Whether you're restoring a vintage C10 or modifying a square-body Sierra, this header set addresses the fundamental limitation of OEM exhaust design on big-block applications.

Flowtech engineered these headers with mandrel-bent primary tubes that maintain consistent diameter throughout the runner length, eliminating the turbulence and backpressure inherent in cast manifolds. The stepped design optimizes scavenging across the RPM band, pulling exhaust more aggressively during acceleration while maintaining low-end torque. Constructed from heavy-duty steel and finished for corrosion resistance, the header tubes are precisely angled to clear engine bay obstructions while maximizing flow—critical on trucks where space constraints demand careful packaging. The 37-pound assembly integrates seamlessly with factory or custom exhaust systems downstream.

These headers suit 396 and 454 big-block applications across the full 1968–1991 GM truck platform, including Chevrolet C10, C20, K5 Blazer, and GMC equivalents. Installation requires basic hand tools and mechanical aptitude; mild modifications to engine bay brackets or firewall may be necessary depending on your specific truck configuration and accessories. Pairing these headers with a quality cat-back exhaust system and engine tuning will yield the most dramatic results, typically adding 15–25 horsepower while improving throttle response and exhaust tone.