I was recording 20 MPG highway, but I have a tonneau cover.

As for your questions about V1 or V2, you could get away with V1 if you dont want to tune anything newer than a LLY style motor in the Duramax lineup. I have V1 and like it, yes I want V2, but I can wait until I get a little more money and better at tuning.

If you get EFI Live and send me your stcok tune I can tune it for a little better mileage and some better top end power. Nothing extreme, I had my truck tuned like that until I destroyed my trans with too much power. Now I run a big tune.

Tony