well so far i was able to squeeze out around 650 miles out before the air dog started to loose suction, just below a 1/4 tank
I got ballsy and drove 800.6 miles with the airdog loosing suction sometimes on hard stops. Filled it up to the usual spot and the pump read 25gals and change. 32mpg
I would have to measure it, but I think it's closer to two inches...so you may not be so good. LOL
new goal of 40mpg is on the way