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. Manifold #7107 is designed to fit 1992-1997 GM LT1 engines, and is matched to our Performer LT1 cylinder heads #61909. If using OEM cylinder heads, gasket matching of the cylinder head intake ports is recommended for optimum performance. The #7109 is designed for 1994-1995 GM LT4 engines. #7109 will also fit 1992-1997 LT1 engines that have installed LT4 style cylinder heads. The #7109 is matched to our Performer LT4 cylinder heads, #61939. It may also be used with our Performer LT1 cylinder heads #61909, with minor port matching of the cylinder head recommended for optimum performance. With OEM LT4 cylinder head applications, such as 1994-1995 LT4 engines, or 1992-1997 LT1 engines with LT4 heads, port matching of the cylinder head is useful for optimum flow Both manifolds accept stock or aftermarket fuel rails and include an OEM style throttle body pad that will accept oversized throttle bodies up to 58mm.