HOOKER SUPER COMPETITION BLOCK HUGGER HEADER, BLACK -- 1.625 in. O.D. Tube size , 2.5 in. O.D. Collector size; Comes with round shape port; With tuned-length primary tubes for maximum exhaust scavenging and velocity; Mandrel-bent tubing for smooth exhaust flow; Light weight and sturdy 18 gauge tubing; Tight-tuck design for narrow frame rails; Can be used with stock motor mounts, machined flanges for a perfect seal; Designed for optimal performance; All necessary hardware included for a complete and easy installation; Will fit Chevrolet with 350 LS1 engine.