Cheers lads thats a load off my mind, may go with your suggestion n throw a thicker hg on...any idea what the cr would be after the head and block is skimmed + a 1.9mm hg? Bearings id go for acl or clevites..as for the head id just be cleaning the casting marks roughly/port matching mabe even cut the valve guides down but thats it no removal of excess material @ klyfax the reason i want a rebore is to start fresh, so 74.5mm should suffice..emb is emanage blue n emu is emanage ultimate....decided on a ngk wideband and some stack/omori gauges but yet to finalise management When you say port match the top, do you mean just the top half of the port and leave like a step in both inlet+exhaust manifolds? Ive read that having a step in the exhaust manifold-head is a good thing something called exhaust reversion? I have a acis ready to go...a run on each set of runners will easily determine the best open point Apreciate the help guys