So I have this egr spacer that I need to swap out of my DL...its all nice and polished which im lovin the look of. The problem is the one that I have got to put in, isnt and its covered in the usual whiteish corrosion they get. Has anyone had any experience in polishing these...if so how did you do it?.

I know the process as in from harsh to fine grit paper then on to cutting/ buffing compunds...get all the scratches going the one way etc. But what grades of paper/compounds did you use?