Did you have it on the gooseneck?

If so its way taller than the truck unlike on a bumper pull, so that is why coop and JB get good gas mileage?

I bet it opens up after the break-in. Mine was upto about 20-30K before it went from 17 on the hwy to 19 or 20 (sans rigs of course). I get 11-12 with klogger/blazer at 80 with cruise control on the whole way.