high compression

[hulk]

would it be safe to mill the head on a I4 with I/H/E for a little more power?

[WarmAndSCSI]

It won't net you anything, and you're just going to end up messing up your valve timing and clearance and smacking a valve. Not worth it to do it that way.

[Stewi]

Yeah its not the same as running a domed piston. When you mill the head to make your final compression higher, your still decreasing the overall size of the combustion chamber (less volume) so there isnt much gain. In theory it sounds good but your end result wont be as great as it seems.