As much as I like precious metal plugs over the older more conventional plug design, I don't think a design like the E3 brings any benefit to the performance table. In fact I'd almost be concerned with the electrode design possibly shielding the spark a bit depending on how it was indexed. Spark plugs aren't magic, and if fact they may the simplest item in the engine. Improving ignition in an existing engine almost always involves the coil and/or computer manipulation of the spark. As long as the spark plug has sufficient conductive quality and a gap that doesn't prohibit spark jump, there's not a lot more that the plug can do. A hotter spark with more energy is good and in many cases so is a spark that has multiple discharges. The multiple discharge design is what made MSD famous for many years in many engine applications. Oddly, however, many of todays combustion chamber and valve designs in cylinder heads don't benefit as much from multiple spark discharge. And the hotter spark issue isn't always required as long as the engine's existing ignition design is capable igniting combustion. More sophisticated and efficient valve and combustion chamber designs, along with fuel injection, have negated the need for many of these aftermarket ignition devices. Now, when you start manipulting that existing engine with aftermarket mods like a turbo, supercharger, higher compression, and some other more extreme mods that put pressure on the combustion processs, those "older-school" ignition mods "can/might" bring some higher performance back to the existing ignition system on the engine.
Still, the spark plug's contribution to all this is minimal as long as the plug gap and heat range are properly selected. Where the plug quality has its biggest influence is the wear factor over high mileage and how it affects a continued level of performance. This is where precious metal plugs can be a noticeable benefit...not producing more power, but delivering the same power over a longer time. The precious metal referred to wears better and keeps its shape over a longer period of time, thus maintaining the proper spark. Again, this isn't magic either, and in an exaggerated example, it's like using a shovel made out of steel rather than one made of a very hard plastic. Hard plastic can be designed to dig the hole about as good as a steel one, but it obviously won't hold up as well over time. Having an engine with 16 plugs, it would be a realistic advantage IMO to have spark plugs that last over 3 times longer while yielding the same results.
And I speak from a bit of experience with this in my last engine. I had a stroked 350 GM small block to 383 with an MSD ignition in my last truck. Even with a wider plug gap, the precious metal plugs I installed went 100K with no issue, no ignition breakdown under acceleration, and no breakdown under load. In fact when I pulled those plugs for replacement, they appeared to be capable of many more miles. I just didn't feel like pushing the envelope any further. I went another 100K on another set of precious metal plugs and just sold that truck in November with those plugs still in it. A neighbor has that truck now.
And of course, I'm talking about vehicles used primarily for street use here. In the extreme environment of "race only" applications, no one uses plugs for 100K miles. Even a weekend warrior racer might want to replace the plugs more often so as to not leave any stone unturned in the pursuit of every performance advantage. Still, I think it's pretty impressive how long a good precious metal plug can provided sustained performance, even in a modded engine.
