Very interesting.
As I was reading, I kept thinking "What is the difference between the Power button and this mod?"
Once done, do you still have the two settings, Power and not, just both firmer?
Signed,
Generally Mystified About Auto Trannys
;p
from what i can gather, the "power" button in 343's as well as the "ECT" button in the 442's DO actually change the shift points slightly (signal to tcm). it will wait to lock the TC longer, kick out of it easier, and hold rpm higher before upshifting. teh FSM gives the shift point deltas for ECT and normal modes for my '93. i have had little use for my ect button (i'm sure it's not as good as the later "power" button ) but i have also adjusted my kick cable and could be on the tight side, but it is where i like it. i used to have it tighter but lowrange 1-2 was murder and now its firm but but wont' spin wheels in soft stuff and you dont' see your passengers neck snap back in your peripheral on every shift out of 1. i wish i had second start on my 93. oh well.