The Edelbrock Performer RPM Air-Gap LT1/LT4 intake manifolds feature a tunnel-ram design that offers performance increases in the 1500-6500 rpm range. The air-gap design separates the runners from the hot engine oil, resulting in a cooler, denser charge for more power. The 350-7107 is designed to fit 1992-97 GM LT1 engines, and is matched to the performer LT1 cylinder heads (350-61909). If using OEM cylinder heads, gasket matching is recommended for optimum performance. The 350-7109 is designed for 1994-95 LT4 engines. The 350-7109 will also fit the 1992-97 LT1 engines that have LT4 style cylinder heads. The 350-7109 is port matched to the LT4 cylinder heads (350-61939). It may also be used with our performer LT cylinder heads 350-61909, with minor port matching of the cylinder head recommended for optimum performance. Both manifolds will accept stock or aftermarket fuel rails and include an OEM style throttle body pad that will accept oversized throttle bodies up to 58mm.