Scan Gauge will be accurate on any engine IF tire circumferance is taken into account and that difference plugged into it for it to calculate off of. A stock computer would NOT be able to handle that adjustment without recalibrating the speedo or ECU. If Mike is using the truck odo to calculate mileage and has changed tire diameter, then it is not a correct calculation (unless that percentage change has been figured into the equation). His before number might be higher or lower than stated and it is very dependent upon altitude, heat, and driving style.

The most important part of all this is, if you are considering a SC, MPG doesn't matter. You've already bought the wrong vehicle for economy and I promise you with the additional power the SC offers, you will use MORE fuel - any time you step into it, it's going to richen the mixture. Unless you drive it slow and then that begs the question of WHY are you getting it?