[SLESTAK75]

No need to remove the head. Just the intake and exhaust. If you didn't do anything to them then they aren't the same size. Think of the intake like a straw, if you are sucking as much through the straw as much as it is capable of moving then sucking harder isn't going to get more through it. But if you get a bigger straw. So opening that intake and exhaust up allows that head to move as much as its capable of. The exhaust flange you just open up to match the inside of the header and get rid of the ring style gasket. NCY makes a flat performance gasket that can be sized to match the hole. Then on the intake you feel inside while its on the head and wherever you feel a lip just remove metal until the holes are even. Also open up the inner angle of the intake to match. You can see when this is close. No need to remove the head.