1975-1977 Chevelle/Malibu/El Camino, 1975-1981 Camaro/Firebird/Trans Am: (engine swap) 396-502 Tube 2" O.D. x 35", Collector Size 3.5" O.D., Collector Length 10", Port Shape: Same As Port;Tuned-length primary tubes for maximum exhaust scavenging and velocity; Mandrel-bent tubing for smooth exhaust flow; Light weight & sturdy 18 gauge tubing; Long transition collector for decreased back pressure; 5/16” machined flanges for a perfect seal; Industry’s best welds for durability; Designed for optimal performance; All necessary hardware included for a complete installation;