The Edelbrock Performer RPM Air-Gap Intake Manifold 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 rear water outlets, two distributor clamp locations and nitrous bosses. The heater outlet boss is angled for a proper fit over the valve cover. There are no provisions for exhaust-heated chokes and no exhaust crossover. They come with a natural finish. The runners are tuned to move the power band 1, 000 RPM higher than Performer air-gap manifolds, from idle to 5, 500 RPM up to 1, 500-6, 500 RPM.