[cleatus12r]

30K lbs. Been there, done that!

First off, if you're hauling all the time, custom tuning is the only way to fly. The factory programming is designed to cater to operators who do everything from haul (like you do) all the way down to those who do nothing but get groceries with the kids twice a week.

From my first hand experience, when I'm towing a lot of weight, I like my shifts late. I like to have the truck shift at a minimum of 2600 RPM regardless of APP (throttle position). This allows the boost to recover more quickly after a shift. As you're well aware, once boost is gone, it takes a long time to get it back on an early PSD truck.

Secondly, if at all possible, it's nice to have the torque converter lock in 2nd gear under light throttle applications at speeds around 25-27 MPH but NOT lock under moderate load until just before the 2-3 shift. This allows you to have a locked torque converter while driving around town in 2nd gear. Heat is a huge issue and with the "loose" (high stall speeds) of the factory torque converter, there is a TON of heat being made. When the TC is locked, the heat creation is mostly gone.

Third gear should ALWAYS be locked when towing. If the 2-3 shift doesn't occur until the engine is at 2600 RPM, then the TC can be locked and not lug the engine too much. Again, this is to keep the heat down.

4th gear....well, depending on the gearing of the truck, 4th gear should be inhibited until 62-65 MPH. The 3-4 gear change is usually the killer of boost and momentum. If the revs can be kept up, the gear change will be less dramatic.

Forced downshifts should occur earlier in every gear to prevent lugging before the downshift. That way there is less strain during the shift. This is accomplished by raising the downshift speed for a given APP.

I hope this helps a little.