If your stanchions are in bad shape such as nicks, pitting, etc. then you need to have the surface restored before getting any special surface coating applied. You can send them off to be re-chromed where they reapply the hard chromium and grind it down to a new surface. Not sure what that costs but look in the back of MCN for firms that can do this. There should be plenty and people on this board (are there any left?) might have a recommendation or two.
The TiN coating can be done by someone like Tec-Vac and is aroung 60 quid a tube. For DD, I doubt this would be money well spent, but that's only my opinion.
