Upon taking my pegs off, front and rear, I noticed the rear pegs do not have large dampeners like the front ones do. It probably isn't the rubber her feet are sitting on, but rather the fact that the rear pegs are bolted metal-to-metal to the frame.
The bolt that holds the rear pegs on seems to be extra long, so it probably would be possible to ram some rubber washers between it and the frame; you can get these at the big hardware stores in the hardware section with screws and such. Alternatively you could try something aftermarket, but make sure it has some dampening between where the peg attaches to the frame, not just on the foot rest itself.
