12" and 13" props are really too big for this engine. You are going to load it down and not get full power out of it this way. For 3D flying you want a lower pitch prop in the size range for the engine. For the OS 46 you want an 10" or 11" prop, anything from a 4 to a 6 pitch would probably work best.

As I have mentioned to others it's hard to recommend what is "best" for you and your plane. What works well for one person will not work well for another. Your best bet is to get several different props and then try each one. Then settle on the one that best suits your style of flying.

Ken