Originally Posted by 4sevens.com
Yep - sounds like pad deposits from less aggressive pads. Here's a cool trick - if you put on race pads (i.e. pfc01's) and drive it around town or back from the track - it will actually scrub off your rotor clean of deposits. Modern design of rotors these days nearly eliminate rotor warp. You'll cause other damage long before the rotor starts warping unless they're really really worn thin. When I had my OE's I thought my rotors warping but it turns out it was just street pad material getting deposited on the rotor.
Yeah, I don't doubt that deposits are causing the wheel feedback. It's happening way too quickly for the rotors to be warping.
Thanks for the tip on the race pads scrubbing the rotors clean. I would buy some RS19's to attempt with my stock rotors, but I think I'll go BBK and put on the right pads from the start.