RE: Best Prop for Super Sportster
Good recommendations.
I fly mine with a 54 four stroke and a 12 X 5 prop. Not a lot of speed but ery good vertical.
I agree with FH, try the 11 X 5 that you have, if you're happy with the speed I'd get a 12 X 5 which will give the same speed (or nearly) with a bit more vertical.
Dennis-