the tiny exhaust relief holes being blocked give more compression = more power. (just small amount though )
got told on another part of this forum that with my triple the first thing to do is block off those little holes and it will raise compression around 3 to 5 psi.

they are put there to give a better idle it seems, but then who idles a 2 stroke ?.
if your trying for max power then block them off, if your gonna use it as recreation and troll a bit then keep the holes.