if i was you i would go with a b16 head. im just thinking about the aftermarket support. i know gsr heads are about the same but the intake is a little different. so i would go with a b16 head and get it ported. i think the itr and ctr heads are about the same but different in flow ratings. that is why i mentioned porting. because you can pick up a b16 head at a good price and have it ported to be better then the itr or ctr head. but the cams are the big thing. get some type r cams and make some really going power. but if you want to rev it up pretty good go and get the crank balanced and then get you a girdle. and arp rod bolts and you can rev to where you want it too.