I have a Slow Poke 40 built from the kit. I have an OS 46 FX installed which provides plenty of power. Only problem is that I had to add 5 ounces of lead to the nose and a heavy hub spinner to make it balance. It flies great and with a flaperon setup you can make it fly really slow. Does almost a flat turn. It does land a little different from most 40 size planes in that you need to keep a couple of clicks of power on it while landing. You'll get used to it though. I would recommend a 4 stroke engine to help it fly slower.

I have a 60 size Ultra Stick with a YS 91 that flies even slower and lands super slow..

LOL