I would never use anything more course than 600 grade on ally. You would be surprised how quick 1500's or 2000's used wet will remove most scratches etc
....and another thumbs up for Meguiars NXT (keeps the M3's tailpipes gleaming, inside AND out. How anal is that? )
Although Autosol is good, and no one has mentioned 'Duraglit' ...it's one worth trying. The impregnated wadding makes it ideal for that 'final finish'
I did mine by hand, its surprising how quick 1500, or 2000's works when wet and the marks are very easy to polish out with NXT or similar.
Thats some nice work in your pics
I wouldnt like to tackle some of those grinding marks on your bits by hand though :shock: Remeber my bits were done at home over the sink and then finished off with polish sat in front of the TV I have no doubght that someone with profesional equipment would go about it differently ...