Sid,
Thanks for the explanation. Now the numbers come alive.
As to the angles of the E-port:
Sound pressure waves do not mind angles, however sharp. They dislike sudden cross section changes, which are evident with the just opened port whichever way you look at it. Angled ports don't help here.
Gas flow in a cylinder is rather stagnant, but it indeed follows the piston for the expansion front. The funny part is, that gas flow will not exceed piston speed, which is about 20m/sec at port open time. The gas flow speed out of the port however will be equal to sonic, as long as the pressure difference ratio is 1.4! That puny 20 m/sec now have very little influence, if any at all, because the speed is present before the venturi formed by the piston crown and port upper edge. Look at it like a slug of high pressure gas, ready to go any way it can.
I have experimented with port angles, and found no gain or loss in them.