My own experience with exotic spark plugs has not been positive. I've concluded that if you have a car with an ignition system that requires them, then that's what you use.
For an older car with a contemporary ignition system, you're gaining nothing but enriching the pockets of the spark plug maker. You're not gaining any performance advantage over stock requirements.
I think all you need to install is the proper heat range plug of whatever brand spark plug you like. The entire ignition system is no better than its weakest link. Expensive spark plugs won't make up for something lacking elsewhere in the system.
While I haven't seen the tv show or infomercial where they tested the plugs it brings up a question...at what rpm were they able to measure the alleged 3hp increase? Was it at a very high rpm or where you actually drive? Did they test the E3's against a brand new, properly gapped set in the engine or against the plugs that had been in the test engine for 10k miles and who knows what gap they were at? Trying to compare and get answers in a vacuum of information and facts doesn't help.
When someone does a true test of apples against apples I'll pay attention. Spark plugs are designed to allow a spark to jump at the right time. How that's done is still essentially the same after all these years. Technology has made improvements to be sure, but it has to be in context of the entire ignition system and over a period of time to be considered valid, not just in one test.