if you mill the head almost completely flat you will have around 180 psi (i have 183) and that's with 2 base gaskets that i made myself out of thick gasket paper and no porting i was thinking about getting on a puch high comp head since the batavus head has no squish band so the head is basically useless but then it would cool not as good because of the direction of the fins on the puch head so i was then thinking a pug head has the same bolt spacing and fin pattern so i may get a high comp pug head (50cc) since its same bore almost and same bolt spacing so yah there's another "secret" i have