What is the best cleaner to clean the exhaust ends? Picture attached. Thanks

y to clean the exhaust ends

 

I've seen several videos on different detailing sites showing people using an All Purpose Cleaner with a Mother's Powerball cone to clean the inside of round exhaust tips, then using a metal polish on the outside. I would think this would also work with your center exhaust tip with some moderation in technique. A search on the You Tube site may give you some better ideas of how others deal with this problem.