Interesting that you guys are talking about the APC 12.25x3.75 prop. I went to the hobby shop today to get a 12x5 but they were out and I ended up buying the 12.25x3.75 APC instead. If that one ends up working out, I'll have to get taller landing gear to use it. The MACs header for this engine should be here tomorrow or the next day. I have about 48oz through this engine so far and once I hit close to a gallon, I'll put the pipe on it and see what it will do. I'm really impressed with it so far. It seems to have really good transition (low end tuning took some getting used to) and the response is really good. My Little Stick is going to love it I think. I'll get some numbers for the 12.25 APC this weekend and post those up.