I had my maiden flight on my Panacea this weekend. This plane flies great. Every bit as good as my Smaragd-z.

I have set up the Panacea with an OS 160, Hatori wrap around header, Kline regulator and the OS 140 pipe. I am having a fuel draw problem and the pipe seems peaky. When the engine is on the pipe, I have plenty of vertical. Some times the engine will not come back on the pipe when transitioning from low throttle thru mid range. I have a very reliable and low rpm idle. The fuel tank is mounted over the wing tube on the CG point. No problems in transition when I test the engine on the ground. Currently the pipe is mated to the Hatori header with no additional length. What is the best pipe tuning length for this engine.