Can't get my black exhaust tips clean

I have dual black tips I bought on Amazon. They were gloss black originally but went hazy pretty quickly. Is there a good product that I can get these clean with? Or at least see if it's NOT just dirt and oxidization. I suppose they could just be faded, but they've looked like they do since about 3 months on the truck. I've tried regular auto soap, and some spray on wheel cleaner.

 

I would suggest a good cleaner wax after your regular wash and cleaning. It should have enough bite to help clean up any oxidation and stubborn crud.

 

I had never noticed such a thing existed. I'll pick some up and give it a shot. Thanks!