One of those car TV shows “House Power” I think did some test on one of those expensive plugs and it was found to give a couple extra house power (to like a 500 hp engine). I’m a bit skeptical myself. A search on their website will probably list the plug.

Personally I have not had good experiences with Champion spark plugs in good running motors. One actually fell apart in a motor. However that motor was a blown fuel injected big block