Product details:

Doug Thorley Headers THY-313-C 4:1 long tube headers deliver the ultimate in performance and for your classic Chevelle, El Camino, Camaro, or Nova. 4:1 long tube headers are designed to replace the factory stock exhaust manifolds with a performance component that results in a serious increase in exhaust flow over stock. That better exhaust flow produces noticable gains in horsepower and torque output, while increasing fuel efficiency. The headers are manufactured using heavy duty 14GA tubing, and super flat 3/8 inch head flanges. APPLICATION SPECIFICS: 1966-1974 Chevelle, El Camino / 1967-1974 Camaro / 1968-1974 Nova, 396-454 V8, automatic transmission, will not fit D-port cylinder heads. 1-3/4 inch primary tubes, 3 inch collector outlet.