simple... b18c head will lower compression and b16a head raises... no matter what block the b16a head will be lower than a b18c... but this is good for turbo cars... like me i have a `97 GSR head that i want to trade for a B16... this would make the guy with the B16 have higher compression... this would also give me lower compression... so it is a win win if you find someone to trade like that...
-Keith