bako,it was done by adrenaline powersports out of citrus heights,ca. i think it was $400.00 for the porting.the bike had a diff company dunerport before when it was stock stroke.the difference between then and now is huge.the 4 mil set up i have pulls about 10 bikes on my friends cam mod,sparks exhaust,filrtrered and jetted yfz.the old set up i would get beat by 5 or 6 bikes.