What is the main cause of head gasket failure = excessive boost for components used e.g oem headgasket, oem head bolts . poor tune the list can go on.. bottom end failure = again being unrealistic with the amount of load components can take vs power goals = ticking time bomb. poor tune poor machine work etc etc vtec rev range hmm i think thats around 10000 rpm i havent seen or heard of a 4e or 5e rev too that and live too tell the tale ! but i have seen them rev too 9000 rpm all day long but that involes alot of R&D and money