Your "Chrome" tail pipes are infact polished stainless steel. A real chromed part could easily be cleaned with scouring pad. Used to do this all the chrome with my old MGC but if you use scouring pad on the polished stainless you will soon take the shine off them. On the plus side if you screw them off they will buff back to a bright shine quite easily with a motorised polisher .Always best then to clean these with a good metal polish as used in the house. What scouring pad is very good for though is cleaning up the rear silencer box when it starts to get dirty and stained. I do this about once a month and it really comes up well and looks the part as the rear box is designed to be seen and look a bit like a skid plate.
I used to use wonder wheels alloy cleaner and a nylon dish scrubber on my S4's tailpipes, they were nice and shiny afterwards.
I have just realised that I've not cleaned the pipes on the Treg since I got it. In fact I still need to get the big scrape that I inflicted on the rear arch on Mothers day repaired. Need to get priorities sorted!
Autoglym intensive tar remover appied liberally, leave for 5-10 mins to allow the tar splats to dissolve,(make sure pipes are cold-if rally black a few applications may be needed).Once you have removed the tar residue wipe of excess this ensures no scraches in the tailpipe finish, and polish with solvol autosol metal polish. I have valeted the worst tail pipes you have ever seen and this leaves outstanding results.