+1 on the smaller combustion chamber bit. however, the only real reason ppl say that the b16/itr heads are better is bc they "flow" better. this is only true for the type r head bc its been slightly ported/polished from the factory. the standard b16 head actually flows about the same as the gsr, with each flowing better at different points of lift due to the shape of the ports (according to the flow charts). the b16 head is used to make a poor mans type r bc the b16 and itr heads are from the same casting so the ports are already of similar shape. the casting is the ONLY thing that the b16 head has in common with a itr. other than that EVERYTHING is different. hoped this help clear up some misconceptions.