My 28% Extra had a problem the first time I started it up for a test run. Hitec Aurora 9 2.4 gig radio system. It wildly fluttered ALL the controls to the extent that I thought it was going to damage the servos and/or the controls! What I found was the metal cap on the spark plug hadn't been crimped shut properly, and there was a hairline opening in it. About the width of an Exacto knife blade. I crimped it shut properly, and the interference went away. In all fairness, I had a non-resistor plug in it just for the test run only, but still, it goes to show how important that ignition shielding is, even to 2.4 systems.

AV8TOR