Originally Posted by shifty35
The biggest issue is compression... if you want to boost, do the Z6 head, no matter what, as it will give you lower compression, which is ultimately safer for a boosted car.
neither head swap will be good for the b7 if you plan on boosting. unless u get a thicker head gasket. say .05" and thicker.
b7/z6=10.1
b7/y8=10.5
y7/z6=9.6
y7/y8=9.9
^all using an oem headgasket