That class is port CC limited. It has to not exceed a particular volume. The porters job is to then reshape the port to make it more efficient. To gain cross sectional area (which is what limits RPM), common practice it to machine the intake gasket face and make the port shorter. Charlie Wescott did this so much, that they changed the rules and introduced a limit (they machine up to the valve cover holes, he'd almost mill them away).
Yes I understood all that when I watched the video, I just found it interesting to basically spend $50,000 + per engine plus all the R&D just to extend the rpm of the shift points a few hundred plus rpms but I get why though.