That was I was afraid of. I know they are closed chamber heads with allott of porting work and bigger valves. I guess in a few months when I get ready to upgrade the cam to a roller I will find out then. I was told it was 10.7 but when I started researching the heads I found an article that I can't find now that said the combo should put me over 12.1 . I am hoping that is not right.
Sam