RE: OS AX 46 needs more power
IIRC we ran either 9x6 or 9x7 APCs in a very similar class years ago with Vipers and Predators.
There might be better props out there in APC's competition series.
I have found an edge with carbon fiber props from suppliers like Eliminator [Steve Wilk]
APCs are relatively heavy and thick, so they require more power to turn VS well made carbon props. I can take a carbon prop and reduce blade area and see improvement sometimes.