Part of the key to getting a plane that will 3D well is keeping it light. Using the .91 4 stroke just doesn't make sense, the YS .63 is the right motor for this plane with a 13x6 prop it will be perfect. The design of this plane does limit it's 3D capability, but it is still an awesome .40 size plane. What about the Cap? That will get you closer to a real 3D plane. But I still think that you would love the Extra.