Well if you knew what I do to some of my planes, you would ignore me. I have a Saito 100 on the 40 size WM P-51!!! I run a 12x12 prop

Now a guy here also has the Shoestring with a Saito 100. He runs a 14x8 apc. Thats where I would start for a few flights and see how it goes.

I think I have a picture of mine in the "My Models" icon here