I didn't polish mine but I painted it and it came back pretty clean. I didn't even take it off, I just covered the rest around, because you need to make sure there's no gap between the gasket and the cover when you put it back. You gotta make sure it's sealed properly!
yeah I read somewhere else that you're supposed to sand the hell out of it and keep increasing the the grit till you get to like 1200 or something, then you break out the aluminum polish and buff that thing till it shines! [thumb]