ok...all i want to know is what is the difference?? i mean i know your block,and the compression has a lot to do with the power output..but i mean what seperates..getting a geniune ITR head that puts out 200hp...as opposed to getting a b16 head or b18c head..and putting ITR cams in it?? the numbers or power arent gonna match up right? or are they? and then what about aftermarket cams...what about putting aftermarket cams in a gsr head...would the numbers match up to a type r head? im trying to figure out the differences,and why people take these three different routes.