Jeremy, When you speak of the Nelson heavy duty plug are you referring to the flat coil Glo Bee style, or the traditional spring coil "peep eye" plug that has a scribe line cut in the wrench hex? There are several different plugs sold by Henry Nelson, Mike Langlois, and Dub Jett. There was the original Glo Bee that used a separate collet: later there was the single piece Glo Bee: there was a single piece with a standard element: and one with the heavy duty element. The Merlin Glo Bee style plugs are nice, but in my experience don't last as long as the original Glo Bee's. On the occasions that I sport fly my old short strokes, I'll run the heavy duty "peep eye" plugs. As Rudeboy said, try not to peak the engine on the ground before launch, especially if it's an AAC setup. Something happens when they get hot on the ground, that keeps them from making full horse power in the air. Some of the Q-40 racers hold a finger over the venturi to keep the engine rich on the ground before the flag drops. That way they don't have to needle the engine up just before launch.