The factory setting is meant for factory cars and should be used as a minimum preassure to set at. There is a supplemental for road testing and tuning for the transmission. You should be able to give light throttle, approx. 1/8 pedal and you want your 1-2 shift to happen at about 10mph, 2-3 should happen at 30, 3-4 at 50 or so. If it is shifting too soon you need to tighten the cable, too late loosen but don't drop below the min psi setting. Due to tires, gearing etc. we have found that the drive and tune method to get the shift points where they are supposed to be results in a much better driving vehicle. Remember to set by psi first and if it is shifting too late then you need to reduce tire size or increase gear ratio as the transmission depends solely on the TV and governor for shifting. The TV controls the pressure more than it does shift points but they do work together as far as how the valving works with spring pressure etc..