We run NGK-10 plugs in our EFI 565 and are spraying it with 325 hp with a dry kit. We just ran our best ET on the weekend (7.69 @ 178mph). While inspecting the plugs tonight we noticed that there was rust at the base of the plugs where the porcelain meets the metal. Any ideas what causes this? The plugs have been sitting for 5 days in the motor, would condensation have done this?