No. I've never cut anything but the head-to-block surface. Ever. I've never had an issue. Even if you use a .039 thick head gasket, your giving up about .014 to the original head gasket. So your .040 becomes only .026 of a gain, follow??? Like I said, I didn't cut the heads on the 318 I now have in my car because I was keeping the cost under 500 bucks. And i did keep the cost to 497.00 :)