I use autoglym metal polish, but when that runs out I'll be getting some autosol.
I have a standard exhaust system, so no stainless. I'll start by spraying it with a pretty strong mix of wheel cleaning solution inside the pile and on the outside of it throughout the process of washing the car. Now and then I'll just take 20 seconds to give it a hit with the wheel cleaner and do that maybe.. 5 times.
Then I'll pressure wash it down at the end. I'll start with wire wool if I have some to hand, if not I use one of those green abrasive pads you find in the kitchen with some polish. After a while with that, I'll finish it off with the metal polish and a J Cloth or just one of those yellow polishing cloths. No point using microfibres on an exhaust!
I'll usually do the first couple of inches inside the tailpipe too. I can remove the carbon in a couple of minutes using the above process and it makes it look 10x better. I don't do many miles so the carbon has barely built back up by the time I wash it again
