The Rapidfire plugs were developed to cut down on irregular misses by GM engineers who were doing a lot of emission testing and monitoring cylinder-by-cylinder. I believe there are a couple of SAE papers about this. So it is not all smoke and mirrors.

The question of whether you'd notice it on a dyno or racetrack is still up in the air, I'd say probably not. But that isn't measuring as precisely as the tests used to develop the plugs.

If they work in one engine they'll work in others.

I put a new set of highest-end NGK Iridium plugs in my Hyundai and noticed exactly NO mpg increase over the 100K plugs they replaced. When I pulled them out a year later one had the thin wire missing, one had it apparently welded to the ground strap instead of the center electrode, and the other two were OK. Kind of disappointing.

In real life situations, unless the current ignition system is failing or faulty there isn't a whale of a lot of power to be had by any trick ignition.

R.