alright ive got a d16 and i was wondering. i were to take the head off and have it port and polished and 3 angle valve job. i would increase hp right?... well would that extend the life of my head.? in the same sense. if i took my block apart. replace the rings. and acid bathed the whole thing would that extend the life of my motor? im thinkin about doing the rebuild. but i just dont know if its worth it.