I flew my Avistar with an OS 50 SX and a 10x8 prop. I chose a 10" prop instead of an 11" prop to give me some more ground clearance on my hard landings (I tended to bump my prop when I was first learning)! With this combo, I had plenty of thrust and speed. I'm sure the TT .46 isn't quite as powerful as the OS 50 SX, so you may want to drop to a 10X7...