the heads are from the same casting, the only difference is the itr head has a slight port from the factory. otherwise the only differences are valves, springs, and cams.
really? i didnt know that they were interchangable. i just read in a swap post that u can go b16a2 with the gsr head on it.(i think it was the a2) what are the gains from doing this? just more power from a factory head?