If you dont have the head where it will flow enough for the cam then it could hurt... I dont think so for the pro3s in peak hp even though I think pro2s would produce more in mid range on a stock port. But all of skunk products are produced for stock heads, porting would help alot but its not gonna hurt it to do pro3s on a stock port like it would if you went to a high lift roller rocker setup. We did some research first and came up with the fact that go ahead and go pro atleast it will be there and eventually we can send a stock head to rlz