Im running a new YS 63 that I broke in with Wildcat 20/20 YS Blend using a 13x6 Zinger. After a few flights I swapped to the APC14x4W and I like it alot. I did loose maybe 500 RPMs and the rate at which it spools up is just a little slower. But overall the performance seems to be much better. I can hover my 5lb 8oz Flip at just under half throttle and the vertical pull out is very good.

I have only run about 7/10's of the first gallon through this motor as well.

I really like the way the 14x4W slows the plane down. I had a really hard time putting her on the ground with the 13x6 but I had it idled a little high during initial break-in.