I've been very happy with my VMS for over two years now. The tach display has never agreed with the electromechanical gauge on the dash, which is run off the relay terminal of the gear-driven alternator. I have always assumed that the VMS was correct and the gauge was wrong. This week, though, I had occasion to do some calculations (troubleshooting a speed sensor problem) and discovered that when I do the math [ (mph/60)*(tire revs/mile)*(rear end ratio)] to get tail shaft speed, which equals engine RPM in top-gear (1:1) lock-up, I find that the gauge is dead on, and the VMS is reading low. Is this reading a direct number from the DDEC-II, or is there some factor being applied (possibly set on a hidden screen) that could be throwing the number off? At 60mph, with 480 rev/mile tires and a 4.3 rear end, I get 2064RPM, which is just what my gauge reads, but the VMS is displaying 1780. This percentage error is consistent across all gears and speeds. Any insight is appreciated. -Sean http://OurOdyssey.US