Cold in 08 Tacoma - Heater Box TSB?

One of my responses to a previous thread asking for defects or issues related to the fact that for the past 3 winters I've been freezing my ass off even when the truck is warmed up. Three days ago I came across TSB-0072-09 which is the fix for a decrease in air flow out of the vents when the heat is set to full high. Wouldn't you know it, I went outside and set my heat to full cold. When I switched it to full hot, the air volume out of the floor vents decreased by what I estimate is one half. The underseat vents that supply the rear cab hardly emit any air flow at all.

Has anyone had this TSB done? What I am concerned about is that if I increase the air flow through the heater box, does the air come out cooler because air is flowing through the heater box at a faster rate?