BUB started using a different process in 07. The older version was annodized and tended to discolor quickly. The newer version is coated similar to teflon on pots and pans, and with 15,000 miles on my replacements they look as good as new.
I talked to a BUB rep at a bike show and she was the one who told me this.
Powder coating is a process you could try? At least it's relatively cheap.

 

Mine turned color and match my black cherry SG almost perfectly. My HD parts guy wanted to know where I bought them, cuz he can't get that color! Even a blind squirl gets a nut once in a while!!

 

I have 1 copper tip if you are interested.... trade for a black??