dull pipe
You should also try Jassco paint stripper. You can get it at Home Depot.
Brush it on, wait about 10 min. rinse it off, and then polish the pipe with Mothers aluminum polish.
Works like a charm, and is very fast acting.
Another way is to use Carbon Off. You get this at Smart and Final.
Spray it on, rinse the pipe, and polish.
I use both methods, and either one works great, and takes very little time