I think I've got what's going on nailed down more... I think part of the problem is the way auto tranny and the Interceptor thinks.
Accelerating from dead stop or from moderate speeds the Interceptor does a pretty good job and smooths the shifts since the delay allows the tranny to carry more momentum in to the next gear and the line pressure increase creates more positive shifts.
However, lets say the VX is heading into a left (or right) turn where it would be heading uphill immediately after the turn, if you decelerate going into the corner and accelerate (or have to add gas in order to keep your speed heading up the hill) like you're suppose to... the tranny would downshift because of the extra accelerator input. The tranny thinks you want to accelerate so it downshifts. The problem here is the delay forces the tranny to shift late. The VX has lost speed and momentum in the duration and when it finally does downshift it does it harshly and since pedal input hasn't changed, once the shift has been made the VX jolts forward... kind of uneasy feeling when you're on a narrow winding backcountry road. It has the potential of upseting the truck's handling. The best way to describe is probably how it feels when you down shift a manual tranny without matching the RPM.
So... I'm wondering if the culprit is really not the line pressure setting but the amount to delay (too much)? Thoughts?