Oldsmobile 400 425 455 MID-AIR™ MidRise Aluminum Intake Manifold [Polished] The right choice is critical

The right choice is critical for your engine and your wallet--choose Speedmaster iron distributor gears

turbocharged and nitrous applications

these spacers can handle anything your vehicle can dish out

For use with cut velocity stacks

Oldsmobile 400 425 455 MID-AIR™ MidRise Aluminum Intake Manifold [Polished] The right choice is criticalThe Speedmaster MidRise Air design features the identical plenum and runner design as the normal MidRise. The main difference is that there is an open area under the plenum chamber. This feature is sometimes called an air gap design. The air flowing under the plenum provides a cooler charge for the incoming air with less heat transfer from the engine. This cooler air charge provides additional power and torque.