I just spent a few hours cleaning my 4 year old pipes that were a golden hue with lots of road grime, oil, and plastic that the wind blew onto hot rear pipes. I used a grey scotchbrite pad, on removed pipes using Bartenders Friend and lots of elbow grease. They cleaned up nice enough so I used a quick coat of Mothers metal polish to bring out some shine on the SS. It would be better to use a machine to polish them but not a bad shine for what I used.
One question I thought of when I was polishing my exhaust is if SS pipes can be ceramic coated? internally for heat control?