Deffinitly go ls/vtec. As Eric said, best performance per dollar. Also, i suggest the b16 head b/c it seems to have more stuff that will fit it. ITR has a b16 head with a different valve train and mild port job, so the ITR IM/header and stuff fits. With a b18c1 (gsr) head, a itr header needs mods and everytime *i* look at b-series parts, i always see (note: will not fit GSR) and shit. Plus, b16 heads are cheaper!