all a GSR head will give you is a .3 bump in compression.

CTRs are ok in B16 blocks since they dont raise compression too bad. check out my thread on CTR COMPRESSION ratio in the NA forum.

P30s are better, but the availability of CTR pistons makes it hard not to use those.

CPs are nice but that means you have to run aftermarket rods. If your going to go that route you might as well do an LSVTEC or GSR. No use in building a B16 motor, they dont make enough power.