I've seen several guys using 11x4 props on .46 engines with good results. My brother's TT46Pro on a Big Stik 40 performed better with APC 11x4 than anything else he tried. A lot of people like 12x4 or 12.25x3.75 props on their .46 engines but my brother never got good results with them on his. Maybe his engine was "weak" but it didn't like the heavier prop loads.