My choice would be the 46FX! Its almost the same price as the 40FX and a lot better power. I had a 40FX on my LT40 and when the grass hadn't been cut in a while I was wanting for more power to push through. I have trained other flyers with an FX46 on the front and its a great combo! Also helps big time when the wind whips up and starts pushing those big wings around! [8D]