The engine is going to be used in offroad moped racing were most of the winning cylinders are ported polini or athena i forgot zündapp cs25 cylinder which have only a single exaust port. But the ported cylinders often have quite the high exaustport timing. As there are a maximum of 3 gears allowed you need to have quite the wide powerband to have a chance of winning.
I am hoping to achieve that with a large blowdown time area but low timing. The exaust port is extremely wide and shaped for best flow (picture). And yes that limits power, but that isn't terribly important as most other racers have "only" 12hp and with that portlayout and exaustport I am hoping to at least get 14hp but with a exactly as wide or even wider powerband. The pipe is going to be in resonance at quite high rpms somewhere between 12.500 and 13.500 rpm. Also the exaust opening on which the exaust bolts on is an elliptical constriction which helps to keep blowdown velocity high which should also help. Than the constricted ellipse goes over to a normal circular opening.