It's typical for engine builders to raise the piston window ports about 1/8" and not widen it. You want to always limit cutting pistons if it will compromise the integrity (WTF does that mean?) beyond what 1) You know 2) Are willing to spend re-building the engine including crank/rod/bearings/seals, piston(s), and cylinder(s). Having said that, when the piston raises above the cylinder windows, is is good to have a larger area for air/fuel entry into the crankcase. Anyway, when modifying a piston, try to keep the corners radiused- I.E. not sharp corners that concentrate stress. Before you get all excited about the piston window mod, however, starting with a stock engine, realize there is more HP potential in the exhaust port than this window. The exhaust port and then the intake MAIN ports are top of the list- and with them, always make sure they open at the same time (left/right) regardless of port timing. The main ports should open before the aux and boost ports. Another biggie is when putting on a ported cylinder is matching the crankcase (use a gasket to compare/modify). This is usually worth a couple HP depending on the ledge at that point.
