To be fair there may be a lot more going on inside the motor than we realize. Talking with Jim Husted there can be large variations in quality control in the windings, insulations, connections, banding, etc. that can mean the difference in a motor rated for 48 volts originally surviving at 156 volts or more. Not that an individual can't do those tricks themselves on a rebuild but Warp is probably doing a bit more than just advancing brushes and a nice coat of paint.
Lets hope the managers/owners of the forklift parts/scrap yards aren't surfing the web regularly, otherwise the price of 11" motors will be increasing!!!