I also have this plane, it is a very nice plane. I've had it for six months now and I always use between 11x6 - 12x4 props. It wouldn't hurt anything to go bigger. Using a 13x4 prop should do well. Anyways you have a Irvine .53 versus my .46 Thunder Tiger so you can go even go up to around 14 something with that engine. Although when I used the 11x6 prop it flew faster. But of course this a 3-D plane and the bigger the prop the better, especially for hovering techniques only if the engine is powerful enough. So I'd say anything from 10x2 to maybe 14x5 is great. But yeah, I been enjoying this plane alot. I'm thinking about throwing a Saito .72 on it. Just hope I can handle it.