It sounds like the brake pads are making contact with the rotors. The rotors have become slightly warped and out of round. Time to get the rotors machined (turned) and possibly new pads while you're at it. If there isn't enough material left on the rotor to machine them, you'll have to opt for a new set of rotors. They aren't too expensive, and it should solve your problem.

 

Brembo stop making the rear BBK for the SC430 several years ago. But through some digging and persistence I learned that Brembo will make the rear BBK for the SC430 on special order. It take at least four weeks to have the kit made.

 

Yes, that's definitely rotor/pad noise.

 

Great info! thnx!