The exhaust manifolds found in the 1988-1997 Chevrolet/GMC pickups and SUV's were designed to combine the exhaust gasses from each of the cylinders quickly with a manifold that was cost effective to produce. Our long tube 4-1 off-road headers are designed to allow the exhaust gasses to flow more freely from each 4 cylinder bank and combine in a more efficient manner. Tubing has been optimized for the 5.0L(305CI) and 5.7L(350CI) engines. This creates a reduction in cylinder backpressure and improved exhaust gas velocity. These improvements free up lost horsepower and torque. An added benefit is a more performance oriented exhaust sound.