[Marlin]

Hey, at least they're stainless and not chrome!

I clean my S/S tips with just about anything. Brilo pad, steel wool, whatever. Thats the beauty of it, it's very durable.
As for a coaing to minimise the grime, I can't attest to trying anything.

I don't feel you'd have much success in painting it for the murdered look.

 

[Marlin]

i think you'll find that black tips are black chromed, much like wheels.

I could be wrong though?

 

[Marlin]

Hey, if it's only raod grime externally you're concerned about, I'd give them a nice polish, and then wipe Inox over them. It will leave a film and make them easier to clean. The real issue is the heat, burns nearly anything off them.

 

[Marlin]

I know ive seen flat black exhaust tips some where. Thats what id like. It must have been custom.

Powdercoat would last I'd reckon