RCBOZO,

I saw a huge increase in performance with the APC 11x5 over a Master Airscrew 10x6. Top speed dropped a bit but overall flyability (if that means anything) was improved. The 11x5 pulls this thing around with authority. I tried a Zinger 12x4 and saw a drop in performance. It gave me slow take-offs like you mentioned. I would try to improve the tune on your engine and give the 11x5 another shot. By the way, I run Cool Power 15% Heli fuel with a cheap Hobby People #8 glow plug (I can't remember the name). Good luck!