The breakin was easy just run it rich for a few tanks and then slowly start leaning it out, I run OS #8 plugs and Sig 15% heli fuel ( would love to run cool power but I'm only 90 miles from Sig manufacturing so fuel is cheap, Cool Power is like liquid gold here) This engine is very reliable, throttle is very smooth with no hesitation or hickups. The more I fly it the better it gets right now there is very little difference between it and my friends OS 50 other then the TT50 is smoother and from what I've experienced a tad more reliable, but only time will tell.