Now I can feel the different between platium and copper plug.

Placebo effect


The injectors arent going to change the amount of fuel being injected into the cylinder depending on the type of metal the plugs are made of. Plat plugs burn a little bit "tamer" than coppers due to having less resistance to electricity. The copper plug throws a better spark and gets a better burn running more efficient and generating a miniscule amount more HP.

platnium plugs are good for longetivity. That's about it really. The 4.6 igntion was designed for them, so it can run them fine.