There was, at one time, a theory that it was a good idea to have the intake port in the head a little bigger(.060 to .125) than the intake manifold, especially with a big cam with a lot of overlap, so the bottom suface of the intake port would act as a reversion dam during the overlap at low RPMs I have not taken the time to find out if that is a valid idea or not I do know that is way better to have the head port a little bigger than intake port size instead of having the intake manifold port size .030 or bigger than the head port size