I have looked at the "screaming eagle" plugs in the Pro Racing Parts catalogue and wondered if they gave any advantage over the stock plugs or were just a rip off. Costing more makes it better right?
I've got the stock ones an they make the gas go bang every time to what more can OI ask for?
As defined by the "world according to Milwaukee", costing more always makes it better. That's why anything from Harley costs twice what it's really worth.
Here's the simple truth about spark plugs. Iridium and platinum will last longer than plain electrodes. If you plan to leave your plugs in there for 50k or more miles, then by all means buy the high priced stuff. However, if you plan to change your plugs every year like most of us, it not only makes no sense to spend all that extra money but it's actually dumb.
As for all the hokum claims about "hotter sparks" and other magical performance benefits that so many ads trumpet, just remember that famous fellow P.T. Barnum and what he said about people.
Jerry