whats the best thing to use to clean polish up the exhaust ?

or any aluminuim parts?

I heard horse radish was good!!! Seriously..

I heard the wife was a good thing to use

Blue Away (from Frosts) works well if it is heat discolouration. There is also some really expensive acid paste IIRC.

I have just finished mine. It was very discoloured and had no shine.

I used 400grade sanding paper on a disc to take the top off and then Autosol to polish it up. It went quite fast and can be done in an afternoon regardless of exhaust condition. All I would say Is make sure you have plenty of sand paper.

HTH

Biz