A tip here regarding the harness: I went to a junkyard and paid $20 for a scrap TCU, hacked it up and made an adapter for the Baumann (takes some soldering skill and familiarity with printed circuit boards, also the connector diagram). I still have my stock unit and can just put it back in the event of a failure (just keep the TPS idle setting at 1.25V). Valve body mods don't change shift points, except by improving the response time (lag) from the command to the shift. Excessive line pressure increases temperature, and insufficient line pressure will KILL your tranny by slipping clutches. Shifting is controlled by two solenoids - 1st gear: #1 energized; 2nd gear: #1 & 2 energized; 3rd: #2 energized; 4th: none energized. Other solenoids are for: pressure control, torque converter clutch, and coast clutch. The coast clutch provides engine braking in 3rd when O/D is off.