That's interesting. I really don't see the point though. A typical .46 will pull those props just fine so I'd think the extra torque of the .55 wouldn't be put to much use. I say take advantage of that torque and run a bigger prop with more thrust. Maybe a 13x4 for a fun fly/3D plane. Maybe there is some advantage I'm missing though, who knows. Maybe I will experiment one of these days. Since this is a beginners forum though, the recommended prop range is probably a safe place to start.