Hopefully you managed to get an answer somewere else. But if not, and for other SC riders experiencing the same problem. No nothing can be done about the black paint getting grey. The paint is just not heat resistant enough. Untoughtfull of Termignoni. I had the headers (the mufflers didn't suffer) recoated in Ceracote black. Never had a problem since. See pic of mine with the same discoloration.
Harley owners in the States having a similar problem seem to be recommending a product called Pig Spit Original.
