RE: GP Ryan STA
This is the STA-M.
Note that the tank pipes are just below the carb line (this is a Saito 100 and unpumped). Keeping in mind the pic is upside down (or rather, the plane is), when in flight the centre of the tank will be slightly above the carb but still generally in the middle of the tank. Not a problem as far as I can see.
Other posts suggest unpumped is not a problem either.