I'm trying to figure out my mpg difference with my gryphon and then when i get my custom tunes but i dont know what mpg to go by. The gryphon has it at 15.2 right now but my lariat message center has it at 13.2. I just dont know which to believe. I've heard the stock one can be off at times and the fact that the gryphon is plugged directly in the obd port leads me to believe its a little more accurate but i dont know. any body know which is more accurate straight off so i dont have to compute it the old fashion way?