Originally Posted by Todd Putnam

If you remove material from the trailing edge of each brush, (similar to a "timed" cut) torque and rpm increases, which increases watts, (electrical horsepower.)

If you remove material from the leading edge, torque increases, and amp draw and rpm decreases. If you increase torque to a greater degree than you decrease RPM, your overall watts will increase.

You can gain performance by utilizing the above information. I'd suggest keeping the brush faces symetrical, ie: keep the brush cuts/widths the same for both poles.