I have come up with a mod to the stock single 4 manifold that substantually increases hp...what I do is to cut out the partitions between the front and rear barrels of the intake, leaving the center divider intact .... and then smooth out the sides and center partition....on the v8 Buick site they dubbed it the ''Doc dual plane'' mod... there is a sticky that I made up on the mod and how to do it.... under da nailhead section....
cheap power increase .....