The header pipes on a "spare" Bird I have, whilst 'stainless' and off a FI Bird, were all but shot when I removed them as part of a makeover I've been giving her. Thanks to a very generous Member, I acquired an almost brand new set of FI downpipes to replace the old ones.
However, the old ones, in the state they were in were good for fook all really, other than an emergency set so I was in a quandry as to what to do. Tried to physically remove the corrosion ( yes, stainless steel will surface corrode and badly if left as these were), but it was like pissing in the wind so gave that idea up. Then called into local powder coaters ( http://twobrotherscoatings.co.uk ) and they kindly bead blasted them for me. They came up, as expected....dull grey but at least corrosion free. Over the next few weeks, I kept 'avin a go at them with power tool abrasives, hand abrasives, wet and dry, little and often and finally with polishing mops on the bench 'grinder'. They have finished up in what I think is quite a reasonable and acceptable state being quite err, shiney in places, (fortunately the places that matter) and have today been refitted.
Glad I perservered with them now.