I'm in the process of planning out the rear of my truggy thing. A 5 gallon tank is as tall as the fuel cell I plan on, so I see no harm in running one. However, based on 10 or so consecutive educated guesses, a york at idle would take 4-5 minutes to fill it to 120 PSI. Call me a picky bastard but that's too slow. Everyone with a york, if you would, post up your air tank size and how long it takes to go from 0-pressure. I'll run a 2.5 gallon if the 5'er takes too long but there will be almost no space saved by running the smaller tank.