Ok, I know that I don't have as much compression as I could on my puch maxi, and I'm looking to do as much as I can to make it run faster. I want to put new rings on it, but Im new to all this stuff. I've heard from about half the people that I talk to that you have to sand the cylander to make them expand properly, and the other half say you don't. So what's the answer? Also, I heard from someone that you can do it by hand with sandpaper, and I'd rather do that than bring it into a shop, because the one near me is known for screwing everybody's stuff up.