Planning on getting one of these for my 09 3.7 gc. Got 2 questions. The first is there any difference between the 52001 tuner and the 52501 tuner in feature wise or is the only difference the 52501 works out of the box? Also if anybody is using it for their 3.7, do you think its worth it? Like gas mileage wise and power. Heard good things about it. I reset my mpg on my evic every so often and always get 10.5 mpg.