The B16 head is widely considered superior bause Honda polished that head when they did one for their type r. They are both amazing heads, and the GsR flows slightly better out of the box, but in the high end the B16 starts to catch up, and a p & p'd B16 head will almost always put higher flow number than a GsR one. A side effect is that you can buy a Type R intake manifold for cheap and it'll bolt on to the B16 head, but not the GsR one.
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Long story short I wouldn't go so far as to say the PR3 (B16) head is better than the P72 (B18C1), but designed for different things. The B16 has much shorter (but more curvatious) ports better suited to ultimate horsepower, where as the GsR has longer straighter ports that will produce peak torque at a lower rpm, but will fall off in the top end.