Well I've run one tank through the engine and it's not bad for the noise. At the very least it won't be an issue at the little field I'll be flying at. It's a nice engine.

I have yet to finish breakin but I did get one reading of about 11,500 rpm using that prop (9x4). For the most part I was running it very rich and under 11k. We'll see what happens on the next tank when I get a chance to run it again. If flight tests suggest that I should change props I will...but I have no desire for speed with this plane so I certainly won't change the pitch. It's a new experience for me to run an engine of this size. Eventually I'll find what combination works best. I appreciate the suggestions. Still, I was impressed with the video I saw so the 9x4's gonna be my starting point. Someone in another thread suggested that the combat fliers are using different props, but this isn't going on a combat plane it's going on a Mini-3D. The slower I can get this thing to fly the better (but there could be an 8x4 in my future...I'll at least have to try it).