Just to update this thread.
Last year I installed the Fast Forward Automotive? Hasenwerk VSS Korrekt Speed Signal Calibrator that can convert the frequency of one pulse train to another:
http://fastforward.ca/signalprocessors/ (about 2/3 of the way down the page). I installed it, and went for a series of short drives, each time adjusting the converter so that the speedo reading coinsicded with the GPS reading and the OBDII reading. It took two or three tries. That fixed the overspeed cutout problem with the Subaru EMU.
