Just recently bought an OS max fp. 40 on e-bay. I plan on installing it in my four star fourty. What size prop should i run?

MA 10X6

I liked the 11x5 more than the 10x6 on my Tiger 2 with a .40 FP. Slightly better vertical, slower landings. I liked the 10x6 better on my Super Sportster, though.

11X5 APC