o ring grooves on tf heads

The o-ring grooves are for extra sealing on boosted applications. No all heads do not have o-ring grooves in them.

yes, the o ring grooves are so you can run a better, steel re-enforced gasket. That way, the gasket wont blow. I was talking to Ed Curtis about them and he advised me to mil the heads down to get rid of them and run a regular gasket. That way, if you have tuning problems, a head gasket will blow instead of the head messing up.