you will be just fine, depending on what it is already and what head gasket you choose, you will be about 10.2-10.4. my head is decked .050" and i use a HG w/ a thickness of .017 which was the thinnest i could find. this put me at about 10.7:1 I run 94 and have a decent tune and I'm fine, if i run it harder (which i usually do) i put in 2 gallons of race fuel. but at .040" u will be just fine on premium.