i bought some tr6's for my lightning since it's time to change the plugs and i've read most of you guys run them and love them so i thought i'd give them a try. What do i gap them at? it's a completely stock lightning except for a weld in magnaflow muffler. I don't know what they are gapped at from the factory. let alone what i should gap these colder ones at. Let me know thanks guys....also what should i expect to have trouble while changing them....i've changed plugs before just not on a lightning.