Dave, I like the two sensor idea. Have you actually done it on an engine? It would be easy to set up. I'd put the switch in front of the firewall as I am deathly afeared (hillbilly talk) of radio interference. Which muffler do you like for the engine? I was thinking of using an old G-38 Bennett style. I've read where it is supposed to fit right on this engine. I'm a bit low on rpm now, and I think some of it has to do with the stock muffler I'm running. Most guys quoting rpm seem to refer to the square tip Zinger 20-10 (6600-6800 range), so I guess I'll get one to see how things stack up. This is so entertaining, I'll have to tear myself away to begin building the plane soon. Thanks for the tips.