With my quadzilla box I went from 19mpg to 15.5mpg with it just on the 35HP setting. Anyone else go through this? Just wonder if there is something wrong. That driving very conservatively on the interstate at 75. Any input would be helpful.

 

Try slowing down to 70 and see if that helps. I know with my Comp, I get better mileage with it on 3x3 instead of 1x1.

 

take off the quadzilla box and see if the truck recovers its mileage. this way you could pin point the problem to the box.

Pat