A couple of Gryphon questions

[dave-m]

I'm loving my Gryphon and the longer I have it the more my curiosity is raised on a couple of things.

AVG mpg - what is the range that this is averaged over?

Tow tune characteristics - when using the tow tune, one of the things I notice that is different than the stock setup is when on the highway and the elevation starts to drop, previously I let off the gas and just coasted. With the tow tune I can feel the truck slowing down more than before. Is that something to do with the torque converter settings or am I just dreaming it?