The riders comm port cover faded to gray from not having a garage last summer so I decided to try the Mothers Back to Black I have seen mentioned here. It diddnt exactly make it look "new" but did bring some color back to it. Here are photos of before, after one application, and after two.
Mine did the same thing and I have a garage. Everything else on the bike looks close to new except this cover. Pisses me off. I was hoping for better results.