I recently bought an 07 GSA with 18K. Both front & rear brakes have a low speed surge/pulse. The rotors were replaced under warranty at 10k. I read a suggestion to sand the rotors for pad residue. This fixed about 50% of the surging. Any suggestions on aftermarket pads to deal with this or do I need check runout on rotors next. At this point it's a small annoyance, not a safety issue. Braking is completely smooth until about 20 mph. Just wondering, I can see an RT needing stainless rotors but wouldn't a GS look better with rusty cast iron rotors??