ChrisMC specifically. You were talking about oversized exhaust valves, why exhaust rather than inlet? usually on NA engines you get more return from oversized inlet valves as the exhaust gases are forced out under pressure as opposed to the inlet valve having to suck air/fuel in. Are you getting both e and i valves increased? Who is doing the subsequent seat/port work? What size are you going for? Anyone got a BVH and have experience of the SVH prior to it?