Interesting question, yes Wiseco does make full circle pistons with the lightening holes in the inside rather than cast reliefs like the stock piston has. I think that for your model the Pro-Lite has lightening holes from the outside. Does it matter? Yes but more so on a 125cc bike. On the 500 its possible that at some time in the rpm range a compression wave will travel through the minor gap between the ports when they overlap and enter the crankcase via the transfers. But that normally happens on all 2-strokes and the effect varies with the tuning of the engine. Let me put it this way, if it was a big problem the reed petals would get burnt and frayed on the edges.