Tim, I tested 16, 17 and 18” props on my X8 with KDE 4012 motors at about 25lbs. My results clearly indicated that with my copter, 16” props were going to yield the best results, mostly because 25lbs is the highest that I’ll fly. Usually I’m flying at 21 or 22 pounds, and at that weight it’s hovering at not much above 50%, and that’s with substandard batteries (not going to derail this thread). But I’d strongly suggest buying maybe some cheaper CF props (like Fox Supreme Lights) and testing with those. The Tigers will do better than the Fox props, but at 3x the cost, I wasn’t willing to make that kind of investment for just a few flights. I think I’m going to be very happy with the 16” Tigers when I can actually get ahold of them. And for the time being the cheap Fox CF props are working great.