The OS will do fine on even 16 oz or 20 oz. I flew it on another plane w/ a 24 oz tank before and the flight lasted like 20 minutes.

If you get the OS 160, make sure you get the Jett Turbo In-cowl muffler, as it provides adequate back pressure and some power boost. Swing a good 20x6 prop at 8000 rpm and get 20 lb of thrust. Keep the plane at 13 lb. It will do the high-alpha thing better than if you were at 15 lb.

Many OS 160 users, including me, don't realize the full potential of the OS 160 until a 20x6 prop is used. I used to run like 18x6 @ 9k or 18x8 @ mid 8k, which does not give the most thrust on this motor.