Not good for performance , I`m sure you`ve done a before and after on a flow bench , those are killers for flow.
My buddy is a great head man (ex 18 time national record holder) and has a state of the art valve/head machine , I saw personally the diff , between that lip , about the size of a clipped heavy fingernail on the flow bench , then w/o it , was almost unbelieveable.
I wouldn`t let anyone use stones for a valve job anymore .-----On any head of mine.. I guess a stock engine type build would be all right for some uses tho.
Just me .
