I have a 2005 620. I noticed while riding with the face shield up (I can hear with it up) that there's a noise (kind of like a whine or a light buzz when front braking. Sounds like it's coming from the master cylinder. Is that normal? It's only when I engage the brake. As soon as I let go it stops immediately.
Pretty normal with drilled rotors.
A zizzz noise is very tipical coming from your cross drilled rotors. Nothing to worry about.
Great... thanks for the insight.