A while back I had strange misfires... Turned out to be 2 cracked plugs (BKR6E)
So I had a spare set of BKR7E laying around that I put in for temporary use. Ive been running them for the past few months until today when i finally decided to drop the $7.50 for a new set of BKR6E's. BKR7E plugs are actually a heat range cooler than what is recomended to be used with my mods. BKR7E is really a BT plug. But the difference is amazing for me. The damn car pulls a lot harder now and even sooner throtle response. I never noticed the difference between 6E and 7E when i switched cuz the misfires were keeping me from going WOT for a couple weeks. Soooo.... Just wanted to share my experience about that... I guess if you are chipped k03, stick with BKR6E's if copper is your preference like it is mine.That is all.