I was talking to Don Potter today about the Z heads. For you turbo guys this will be interesting. He is able to extract 600hp from only 14-15psi of boost and can run 28 degrees total timing at 24 psi of boost. What the ****! Anyway, his heads go for $6000-$8000 and include complete chamber redesign, complete port and bowl redesign, custom grind cam, roller rockers($75 per), and some other goodies. Maybe that is why he is almost able to extract close to 400hp from an n/a motor. He told me I must have head problems to be detonating at such low advance numbers. Kind of makes me not want to run my head now! I'm Scared!