I am planning to put a new piston in my 2003 ktm 520exc (yes I know they supposedly didn't make an 03 520 but that is what my vin says). I was thinking about upping the compression...what is the highest compression ratio that you can still run pump gas? Is there anything else (within a $400 budget) that I should do while I have the cylinder off??? Port and polish? Over bore and run a larger displacement?