b16a2 and type r are the same castings. Type R is hand ported from the factory and has lighter valvetrain and bigger cams. Gsr has higher compression bowl and ports flow good for torque. If the b16 head is so great then why didnt they use it on the GSR???
there is alot of debate and i guess its matter of opinion but all the bigname builders will tell you the gsr performs better and gives you a bump in compression.