[Luce]

Let me take a stab at the high velocity port explanation....

In the first half of the intake stroke, there's a vacuum in the cylinbder and the intake charge is accelerating. Toward the end of the intake stroke, the piston is decelerating, and the intake charge has built up momentum. The inertia of the intake charge continues to ram itself into the cylinder, even though there is no more vacuum in there. Actually, between the resonant frequency of the intake runner, and the inertia of the charge is there, the cylinder can actually be "supercharged", in the sense that the engine will have better than 100% volumetric efficiency.

Inertia is proportional to velocity squared, so you really want the velocity without sacrificing too much flow.