Pontiac 326 350 389 400 428 455 MID-AIR™ MidRise Aluminum Intake Manifold [Polished] They are manufactured from machined

They are manufactured from machined steel and offer excellent valve spring location

They're available in -3 AN sizes in a variety of lengths

Speedmaster idle air control motor adapters allow GM-style idle air control motors to be used with throttle bodies originally designed for a different bolt pattern

These gaskets feature superior-quality rubber and steel

This manifold will typically produce more power than any similar competitive manifold due to larger ports and runners

Pontiac 326 350 389 400 428 455 MID-AIR™ MidRise Aluminum Intake Manifold [Polished] They are manufactured from machinedThe 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.