and they seem like an ok unit for the price. i went a googling for the manual and you need to know how many pulses per mile is sent from the Vehicle Speed Sensor. The 300 has one of these VSS but i have no idea what the rate is of PPM pulses per mile. this unit can be set to 2000, 4000 , 5000 , 8000 PPM
anyone have any knowledge on this and like to share?