I would like to comment on Mr Cregger's remarks. I think he is right about this engine not being designed for the higher rpm's and crisp throttle response that is necessary for 3D. Although I have this engine on a F90, I like it fine flying as a sport plane, with the throttle stick basically left alone at around 1/2 stick. I knew before I bought this engine that it had these types of issues, so I am not disappointed at all. The plane flies about the same with either the 18-8 or the 18-6, but it pulls more like a four stroke with the higher pitch. I'm still in the break in process, so there is room for improvement. If the engine never runs any better than it does right now, I will be satisfied. However, I think I can get it better without too much trouble. I think I'll try my VP 30 pump on it anyway, just to satisfy my own curiosity. Who knows, maybe we can all learn something from this.