DIC's are off, sometimes by A LOT! Your next problem is the canned tuner crap. If you want to monitor EGTs or what ever else, get an Insight. For tuning nothing beats EFI Live, ever. Next step is picking a tuner, like Kory Willis at PPEI or Idaho Rob at ATP Trucks. Mileage is dependent on the driver but most guys pick up a few MPGs over stock. I have seen 21 MPGs running the 120 tune in my CCDRW, but again its all on the driver. Best thing about EFI is its totally custom. You can have it fine tuned for exactly what you what.