I have had at least 4 engines in that size and the best prop for 3-D, especially hovering (and dont forget speed control) is by far the Zinger 17X5. I know Zinger has a bad rep for lacking ultimate pulling power, but thats not where its at with 3-D. Quick spool up as previoulsy mentioned and a good clean transition in the mid range is all important. You can even use APC prop to trace over the Zinger tips, then trim the tips to match the taper for even better spool up.(unloading the prop). Balancing of course is a must.