ORIGINAL: Stormovic
Put a .52 4 stroke in it and that will be plenty. I have a 5th scale Sig cub with the .52 and it is perfect. Nothing looks sillier than a Piper j3 flying like a pattern ship.
YES! I have a .40 size cub flying great with a Magnium .52 4 stroke I picked up for $99. It has been flying since the Mag. .52 first came out. I just replaced the ring this year because the idle was becoming un-reliable. The new ring brought it back to life.
GO with a .52 4 stroke.