The manual claims you can make speedo adjustments, Im going to call them today
As far the tuner goes, "performance mode" really gives the truck some pep. I can now get on the gas below 2,000 rpms and it picks up pretty quick. Before hand it would bog.
However, I really just bought it for the fuel savings. I have it on "mileage xs mode" now and im waiting to burn through this tank and see what im getting. I was getting about 15.5 all city mpg beforehand (don't really do any highway driving). If it gets me up to 17 mpg ill be happy.
Im down to a quarter tank so the numbers will be coming soon