My friend had a question he asked me and i was'nt quit sure of the answer so maybe you guys can help me help him. He recently purchased a 1990 crx hf with a d15b6 he just wants to do bolt on mods to gain hp. He asked me if we can put a vtec head on his car because i'm doin a ls/vtec build i was wondering if a d16z6 head on his d15b6 if so what do you do to do it and if not what head should we go with ?