Ya, I agree with going to carbon fiber blades and or a BL setup. You could also try out a pair of sym wood blades before you shell out for a pair of CFs. Besides, the plasti blades are more for sym blade training then for outright 3D flight, IIRC.

Also double check that the Tx throttle range or limit (if applicable) is set so that the motor reaches peak rpm. I'm sure that you've check this, but thought I'd mention it anyway.