Not trying to bash, but you stated to pt the factory plugs in your vehicle but you are telling everyone to put copper plugs in their vehicels? sounds kind of redundant to me. Autolite makes the best plug, period. I pulled motorcraft platinums out and threw some Autolite double platinums back in. It was running great and is still running great if not better now after the autolite double platinums.
The only reason I would run copper plug if i was driving a race car or if i had some type of forced induction or nitrous. So lets face it. This is a focus website and a big majority of people's focus on this website are not race cars. you are not going to squeeze out more power by using copper plugs. no noticable gains will be had. why not just put in what they were designed for?