the coppers i run aren't 10 for 6 jobies they cost about $45 for the set i think. i've been running them for about 4000kms good as gold and had the power fc put on during that period. The plugs are R5671A-8 . Cam, the bloke that put me onto them tunes cars and runs the same plugs in his brothers gtr i think its sau33 number plates. But hey do what you want i'm only speaking from my experience.