If you have one the ST will be fine and give you all the Power you will want. The 40 size engine are a little heavy, but will work well. That is another reason I would go with the kit. I had to move my battery behind the wing to keep from adding weight. I khave a rossi 40 on mine If I was going to buy an engine I would say a Speed webra 32. I would go with an APC 10x6. That prop seem to be in the sweet spot of the supertigre 40 from my exp. Again, add triangle stock to the joints, add the turtal deck, and add at least 1/2 to the rudder and you will have a plane you will love. When you get started, drop me a pm and I will be glad to walk you thru the whole build.

Freebird