Locks at 25mph, unlocks at 21mph?

That's part of it.

The way I have it set up, the TC will lock at 25-27 MPH under ANY load. It will also unlock earlier than it would unlock with factory programming. I did this because I drive on dirt roads a lot that are littered with hills. So putting the transmission in manual 2nd will allow me a TC-locked good ol' time without any heating issues. As long as I maintain 22-23 MPH, I have a locked TC. If I encounter any hills that cause me to slow down, then the TC will unlock and not cause me to bog down.

Of course, if I accelerate slowly, it also causes me to have a locked TC at all times above 22 or so MPH. My transmission temps are never an issue....even with the stock cooler setup.