For Chevy Suv/Pickup Truck 4.8L/5.3L V8 1500 Stainless Steel Exhaust Header The exhaust manifolds found in the 1999-2005 Chevrolet / GMC Pickups and SUVs were designed to combine the exhaust gasses from each of the cylinders quickly with a manifold that was cost effective to produce Our 4-1 Shorty Style 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 4.8L and 5.3L engines. This creates a reduction in cylinder backpressure and improved exhaust gas velocity These improvements free up lost horsepower and torque