I value your opinion Duke BUT I have to say that I am using the Bosch +4 copper plugs and I can honestly say its not a marketing gimmick. Its been on for about 5k miles and they are not fouling, the idle is smoother and the acceleration is better. Note this is not because I switched from old plugs. I actually had new regular DCO plugs in there for 1K and I took them out and put them aside just to give these a try. I was expecting the worse and I'm pleasantly surprised.
Platinums on the other hand my car hates with extreme prejudice