ok, my friend has a z6 head. I havea 89 crx hf(8v) Willl the z6 head fit. I'[ve been told by some yes some no.. They said that the hf pistons only have 2 reliefs for the valves per piston instead of 4 so a 16valve head won't work becuase theres not 4 reliefs per pistion.. is this true??? if so what can I do to make the HF faster??? thanks, Joe