Ok so i now have equired a m30 b34 from a 635csi! So the point being it has a stuck valve and has had for some time from the amount of build up on the manifold and exhaust port!but thats besides the point im going with an s28 head anyways but with a low compression b34 block and an s38 head that will be cammed and port matched and flow tested what kind of boost should i be able to sustane on the rebuilt stock inturnals!