66-91 GM P/U 4WD Exhaust Header

The 66-91 GM P/U 4WD exhaust header is designed specifically for 4WD configurations of full-size General Motors pickup trucks manufactured between 1966 and 1991. This performance component replaces restrictive factory cast-iron manifolds with tuned header tubes that enhance exhaust flow efficiency. Ideal for mechanics and automotive enthusiasts, this upgrade aims to improve throttle response and engine performance.

The exhaust header features mandrel-bent primary tubes that maintain a consistent interior diameter, reducing back-pressure and allowing burned gases to exit the combustion chamber more efficiently than stock manifolds. This design enhances cylinder scavenging and increases volumetric efficiency, particularly beneficial for naturally aspirated engines. The construction utilizes durable steel tubing, ensuring longevity and performance under demanding conditions.

Truck owners utilizing 4WD powertrains from 1966 through 1991 will find this exhaust header particularly advantageous for various applications, including hauling, recovery operations, and off-road performance. By replacing heavier factory components, this header contributes to improved vehicle dynamics and fuel efficiency, making it a valuable upgrade for classic GM work trucks.