Prop sizes.
 

On the Dazzler, but an APC 12..25X3.75 on it. It is the PERFECT prop for fun flying with the 46FX. On the Zen, try an APC 11X6 and see how that goes. Or, if you want it to be even faster, put a 10X8 on it. Nothing less than a 10X8 on it though.

Prop sizes.
 

For an iterresting effect on the pattern plane... try the 12.25 X 3.75 there too. ;) Up lines become easier to hold. Down lnes don't gain as much speed. You can almost go through the whole pattern without touching the throttle.

I'm not familiar with the Zen specificly... but the .46 FX using the 12/25 X 3.75 can pull up to 9 lbs vertical, practically unlimited. With a 4*40, (at a bit under 5 lbs...) I was pulling continous inside-outside vertical 8's as long as I wanted at 2/3 throttle.