I used to run an 11X5 on my TT46, till I put a tach on it... spinning it at 14,500 rpm. I dont like speed, I like power, so I decided to try a 12.25 X 3.75 and it spins at 12,500 rpm. I love this new prop. I can now prop hang my LT-40 for almost 2 mins ! Doesnt have any pull out though, but it does hang there ! lol