Hi Guys, thanks for all the suggestions. I thought about tuning the engine while using a pusher prop, but I used a regular tractor prop instead for tuning purposes. One thing I just noticed, though. There is a shim provided with the engine in the box, and it says to use it in hot and humid conditions, or when using over 15% nitro. Well, it's hot and humid in Thailand, and I'm using 15% nitro. I'll try the shim to see if it'll get better or not. I might lose some top end, but if the engine is stable, that's a small tradeoff.