Isnt the Z6 and Y8 jsut about the same head? Or is one better then the other? Just a big discussion my buds and I got into just about 15 minutes ago. And seeing how HCF loves debates lol.

 

Better? They both have their strong points. It's generally accepted that the z6 head is better for turbo. The y8 head has a smaller combustion chamber due to it's quench area. Becasue of this, the y8 is less prone to detonation and is also about half a point higher in compression. Furthermore, the z6 has straight ports called "tumble" ports which are a little better for top end, and the y8 has offset ports called "swirl" ports which tend have have a better bottom.

Does that help?