Get rid of that 11x6 which is like a ball and chain wrapped around your airplane and get an APC 10x4 or 5. I have two airplanes that have the LA 46 and those engines are great using 10x6 but those are .46LA's, your 40LA is going to have a problem with anything more than a 10x5. You went the wrong direction in prop selection when in another thread you said I believe that you originally had a 10x6.

John