that is very true.. although helping an engine breathe better is also a big help.. but for drastic changes like snop said, the port windows height, angle, and width are crucial.. i read up some on mine.. the only port windows i changed where the transfers width.. i didn't go taller with them, i just wanted to add a little grunt and all around usable power.. my gains are good with what i did, but don't get me wrong, if i sent them out to someone to have them professionally ported it would be much better,, but hey my extra power was free, and plus i enjoyed doing it anyway.. i have 3 banshee here and one is stock, one is a cheetah cub bike, and this one is now a diy port job.. make fun if u want, but i know i didn't screw my cylinders up.. i trail ride it anyway so i wasn't looking for an all out drag port or anything.. just to have an edge on my other shee riding buds..