The tailpipe chrome bit on my exhaust was absolutely blackened, have just spent an hour polishing it with Autosol, can not believe the difference its made, sparkly chrome and shiny.
It's much easier (and a lot faster) if you use wire wool.
Buy a "medium" coarseness wool and use it dry, or with a bit of water.. then as it compresses up, you can add some Autosol to make a paste, which will make the pipe shiny.
I dread to think how bad yours was ! I did mine and it only took 10 minutes �� I hadn’t done it for at least 6 months. It is 816 stainless though ! Going by the amount of Autosol used, the two tubes will see the car out.....