I <<used>> to have an avistar with a .46 LA engine (slightly more powerful than the .40 LA). I did run a APC 11X4 from time to time. It was alot of fun. the plane will fly very slow, but have a great climb rate. You could get out of trouble with that prop very nicely. I agree with the others ... buy a bunch of props and try 'em all. Now the 11X4 will go on to a Modeltech Magic with the same .46LA.