I have to install a set of .10 over pistons in my 2003 Polaris 550 fan classic. Should I take my die grinder and polish the ports on the cylinders while I already have the jugs:Guillotine_anim: off? Anything to gain on this or am I just asking for tunning problems, etc??

The only port you should polish is the exhaust port. Any other polishing would be asking for trouble.