Taken from another thread mate;
(I think this was kindly supplied by VC or Jules a while back)1. Spray engine degreaser in and around the exhaust tips. Leave for a good while.
2. Agitate with brush (I use a cheapo alloy brush from halfrauds), wipe.
3. Repeat steps 1 and 2 several times.
4. Start the car up and gently dab the throttle to get rid of any remaining loose crap.
5. Clean using WD40 and MF cloth
6. Dry with cloth and apply polish
7. Work polish using 00-grade wirewool if necessary
8. Work polish using green side of washing up sponge if necessary
9. Work polish using MF cloth
10. Buff off with clean MF cloth