The dropping resistor is in series with the A solenoid to drop the 12V signal from the TCU to about 5V to suit the 3ohm solenoid. The standard resistor is 12 ohms the solenoid is 3 ohms, so 0.8 amps flow in the system, to have the line pressure change, to suit the throttle position.
If we use a higher resistance of 20.6 ohms, the total series resistance is now 23.6 ohms to flow 0.5amps. This increase will have the line pressure 37% higher than it was. The maximum line pressure will not increase, only the lower pressures are increased.
This can help a terminally ill box to survive, in helping the band not to slip in 4th at low speed, but it will also increase the pressure to the C solenoid by the same amount, that can cause the transfer clutch to bind at low speed turning.
As for firming up the shifts. The TCU lowers the line pressure when the shift is to take place, so you are not really fixing the soft change, just making it feel better.
The Quick Change does it right.
it prevents the pressure drop, and the 50% power cut during the shift, to remove the time lag, and allow the shift firmness to suit the throttle position.
Harvey.