i know they advertise this, but im skeptical as to whether it really does increase the duramax's fuel economy. Have any of you had increased fuel economy with any of these?

welcome aboard, please post in the correct sections, thanks.

My mileage is probably worse- with all of that extra power on tap its hard to resist. I never make it very far into my "OK.... this tank, I will baby it to get the best mileage.":(

im with speedster twin. if you fill the tank and get on the highway and go the answer is yes if you keep it under 70.

I've seen a mileage improvement. Not huge, about 1mpg in town and 1.5 on the road, but it's there at all speeds. I don't dip into the power regularly, but drive pretty much as I did before, which probably explains why I see benefits that others might miss. But, my, when you need to leg it, what a kick in the arse.

TC

Whenever you increse torque your using less power to move therefor less gas and better fuel economy. The only thing is you must drive exactly how you did before the chip. Which is impossible. With both my chips on high I hit the highway and my butt is flat against the seat. Hope it helps, I read about this in one of my mags this past weekend so no credit for me