Correct Truck, I have been using these 10mm plug caps since 1997 and have never had an issue. Then again I am really careful when installing and removing them. I do like the idea of running a separate ground wire though. About 15 years ago I got my hands on a D&B 5.1 twin. Awesome engine except that it used no plug caps at all, just a small clip. My setup at the time was dual Hitec supreme 8 receivers. As you would guess, no joy in the range test. This had all separate components with the ignition battery and switch just behind the cowl, the receivers and batteries were located behind the wing TE. That was about 20" separation. A call to DA got me a couple of used plug wires and caps off an old 3W ignition. Threw those on the D&B ignition and grounded the plug shielding to the engine case as the ignition was mounted to the engine backplate. Worked like a charm and I got many glitch free flights with FM of all things.