Using what? These Diamond Fire plugs?
Prove it. Give me a Motorcraft (or its Autolite equivalent...After all, that's who makes Motorcraft) part number and only then will I believe it.
Or just a vehicle application that would have had them installed as original equipment would suffice.
Not exactly...It's what's known as a "beam electrode" design, engineered for better durability under conditions when the ground electrode could possibly get so hot that it would actually come off the plug.
It has nothing to do with flame propagation, emissions, or anything to that effect.
Ford Racing now has a "one colder" plug for this application (4.6/5.4 3-valve engines in Mustangs and F-series) and I'll agree it's a wierd looking plug, but not exactly the same as a E3 plug, and not being used for the reasons that E3 claims their plugs will do. It's simply a matter of durability under severe conditions, and nothing else.
I think I remember Champion or another mass-market manufacturer offering the same sort of plugs as an "E-Z-Start" line. They only offered it in a few sizes ... pretty sure I still have one of those plugs.
I'm with GT Mike in that whatever electrode you use, you need to allow the spark an "unshielded view" to the center of the combustion chamber. That's why I really don't like these funky-shaped, side-electrode plugs.
Splitfire was the worst and the cr@ppy things would begin to corrode the week after you put them in.