i started polishing my plenum lastnight and i sanded it all down with an electric sander and today i bought a buffer that fits into my drill and started buffing the plenum with this aluminum polish i got at home depot. so far i probably been working on it for 3 hours and i hardly see a difference. i'm very disappointed. i know this is a long process, but i thought i would see some kind of improvement. am i doing something wrong. please help me

 

I don't think you are gonna get anywhere with that aluminum polish if you just finished sanding. I got ahold of these compound "bricks" used to polish metals like stainless, aluminum etc. The first was a red color, pretty gritty stuff but cut the haze fast. Then on to the green stuff that got the plenum nice and shiney. Finally the white brick which was like a glazing or final polishing.
I also used some professional polishing discs, like you'd find on a bench top buffer. I just adapted them to my electric drill.
Different grit jewelers rouge also works pretty well.