Yup! , I get the same mileage . I have a 06 1500 M/C 4x4 5.7L gaser with 305 rubber on it.
I don't even gun it hard and try to take it easy but I'm just kidding myself in the end. I even thought the E3 sparks would help, but that didn't change much and less than 1 year later I changed back to stock sparks.
So far 12mpg is the every day normal life and I've had the mega for 4 years.
Hope this helps