Quote Originally Posted by EJ1 View Post
From my understanding copper is the way to go, It puts out a better and stronger spark. Guys on skylines Australia recommend nothing but them which should say something.
It's because if you are running a rich fuel mixture because of high boost pressure, then the plugs could foul quicker. Higher combustion temperatures also cause the electrode to wear quicker. So it makes sense to change it more often for less dollars.