The Edelbrock Performer RPM Air-Gap Intake Manifold incorporates the same race-winning technology thats been used on Edelbrock Victor Series competition intakes for years. The air-gap design features an open air space that separates the runners from the hot engine oil resulting in a cooler, denser charge for more power. It includes nitrous bosses and has no provision for exhaust heated chokes and no exhaust crossover. Aftermarket 4-bbl carburetors are not compatible with Auto Overdrive Transmission (AOD) unless used with Lokar bracket SRK-4000. The runners are tuned to move the power band 1, 000 RPM higher than Performer Air-Gap manifolds, from idle-5, 500 RPM up to 1, 500-6, 500 RPM.