This PCE manifold is an ideal street manifold. When used with stock cams it can produce good mid-range torque improvements. With cams that will allow the engine to rev to at least 6,300 RPM, as much as 20 additional horsepower is available with this manifold. This manifold is a bolt-in replacement for the stock manifold on 1999-'04 engines but can be used on earlier engines if '99 or later heads are used. Note that we also offer an adapter kit that will allow this manifold to be used on a 5.4L 2V engine. We also have an upper plenum, throttle bodies, and fuel rail kits for these engines. We offer the PCE148.1028 center plenum as a separate part for those tuners who feel they can improve the flow of this manifold.