I don't know. I've not had the heads in my hands after the porting or after Brett put the bigger intake valve and the smaller exhaust valve. Larry Smith ported them before he passed away. Brett agreed to put valves in them and finish them up. He wanted to try something different. So he put a bigger intake valve 2.125" and a smaller exhaust valve. After he opened the throat up for the bigger valve they flowed around 350 cfm on the intake at .600 lift. He said that Larry's port job looked good so he didn't change any of that.