Mine also does a really tight spin. Usually ending in a dead stick, because the engine died. I've yet to figure it out, thought of using a check valve on the pressure line to the tank. Verticle is really good with the 46fx MAC muffler and 11x4 power point.

I just kept adding alittle lead till I had to start using expo on the elevator. But it needs alittle right thrust. Mixing flapperons helps with waterfalls but they aren't really tight.