Kickdown issue

The PT KD is NOT required for WOT kickdown. It is called a Part-Throttle kd so that you do not HAVE to floor it.

Some shift kits crank the line pressure up quite a bit, and eliminate the Governor pressure. Now, the kickdown linkage controls the Throttle pressure, to increase the pressures to the various clutches, when the engine sees a load increase. The governor pressure controls the rpm at which upshifts occur, and synchronizes the commands with the roadspeed; and it is in conflict with the throttle pressure.
In other words, if the throttle pressure system is calling for an increase of 15 psi, but the governor is calling for a shift at the same psi, no shift will occur.
The governor, has to be calibrated to the rear end ratio, then adjusted to work with new VB calibration.
There are AFAIK only three governor flyweights provided by Chrysler, to be matched to about 8 rear ratios, so you have quite a bit of matching to do. So most kits I have seen, provide details of how to eliminate the governor, making it a manual-shift VB.
Personally I love a well-calibrated governor working together with the PT KD valve. I think it it's worth at least 4 attempts to getting it right, lol.
Personally, I do not like a full-time manual-shift routine.
To make adjusting the line pressure easy, I drilled and tapped an access port in the trans case, right where the allen key needs to go. Unfortunately, on a Mopar trans, the rear extension has to come right off to service the governor.

Oh I should mention, that if you still have a full-auto VB, and the governor flies apart, then the trans will auto-shift gears extremely early and offer no KD.

I'm not an automatic guy, so not 100% sure if I got it all correct, but pretty sure, lol.