... and Loony, is it necessary to use the acid (take that whichever way you want) before the blackness is baked on over several thousand k's?
Betty the hydrochloric acid will clean off the baked blackness. especially if it's used at full strength. Will also eat through any kind of coating on the pipes. Which I guess is the point - getting rid of the factory coating. Just means lots of polishing. Will eat anything else it comes into contact with - paint etc. Will also cause steel to rust if not rinsed completely off.
I just leave mine and try not to look at it. But may try a acid patch test soon (on bike not me).