Proflow Intake Manifold, Max Jr, Single Plane, Aluminium, Black, Square Bore, SB For Ford, 289, 302W. Power bands range from 3,500 to 7,000 rpm, on up to 4,500 to 8,000 rpm. There are applications for small block and big block engines, as well as for 2-barrel and 4-barrel carburetors.