I am sure you will love the .55 AX

I have the 55 in my H9 Arrow and it is perfect. I have run over 3-gallons though it and it has not dead-sticked on my once!

Mine is not transistioning from low-speed to high-speed very well, so I still have a bit of tunning up to do.

My arrow seems to do very well with an 11X6 prop, although I have to be careful about flutter on the ailerons. I tried an 11X5 and it seemed not to have quite as much top speed as the 11X6. I tried a 12X7 and that seemed to be too much. I did not have a tach, but it seemed the revs were down and in a dive you could hear it rev up.