My opinion is that a 30cc gasser would be too much engine for this airframe, but that seems to be the trend. TF recommends 25cc max in 2 and 4 stroke power, (they don't even list gas as a option) so 30cc in gas would be about right because gas power does not produce the same amount of power as 2 and 4 stroke engines. Gas is less power. When I say "too much", I'm talking about the extra shake and rattle that's going to be transferred to the fiberglass fuselage. Not sure if the glass is thick and stiff enough to handle a larger gas engine. It would probably be ok, as I'm sure their are plenty flying with gas power. I would just be concerned about the glass fuselage. My friend has one that he is planning on putting a OS 1.60 twin 4 stroke in, and it has the power of a strong 1.20 4 stroke. Matt Chapman put a OS 1.60fx 2 stroke in his and said it was way overpowered with it. When he flew it, he rarely went over 1/2 power for normal flying. Good luck!