Can anyone tell me how true this is? I was talking to a guy who said he had a buddy that put an Edge on his 04.5 Cummins and he went from 17.3 mpg to 20.2 mpg right away. I know driving style is everything, but this sounds a little.....untruthful even if you did baby it. Maybe all of you can shed a little more light to it and give me a little more info on any other upgrades/enhancements/problems with using an aftermarket module.

not true, i am a beta tester right now and i have not seen any mpg improvement. he only improvement i have seen is the number of codes and wacky crap this thing is doing everytime i drive the truck.

I suspect your buddy was reading his MPG off the overhead counter. Fueling boxes have a tendency to fool the overhead into thinking it is getting better fuel mileage than what it is. Edge only states a 10% gain which only amounts to 1-2 mpg at best. 3 mpg is an awful lot of change.

I have a 99 with the edge comp box. I uses the throttle position sensor to help calculate milage. If you don't use as much throttle to get the same amount of fuel it will think your getting great economy and give you around 2mpg more on the overhead readout. You will notice this right away which I suspect is what is happening. Check it at the pump. You will probably see it's off.

Thanks.....everything I read supports the 1-2mpg gain. I just had the Flash put on my truck, and it is well worth it. The center console is now about .2 to .34 mpg off, not 1.7mpg off!!! Big improvement. Also noticed a little better shifting and starting. For any of you with the 04.5 (600) you might want to check it out.