Why is normal practice to plane the intake when the heads have been milled? A buddy of mine w a machine shop up here in Maine planes the intake side of the head so ootb intakes will bolt rite on. Only dif. is you cant use the cork on the front and rear of the intake. Once the intake has been planed its pretty much ruined for another engine. Just wondering why. Figured id throw that out there for people to ponder.