Ok, I have searched for hours and haven't found the real answer I'm looking for. My friend said my car was smoking the other day, so I let him drive and got behind him. Sure enough, in the higher rpm range, it's blowing out black smoke very noticeably. Seems not to when driving normal. My car has Bosch Platinum (I guess)plugs with the 2 electrodes on the end. Would putting in regular NGK's possibly stop this? If the gap isn't perfect would it cause this? If not, what other suggestions do you have? By the way, my exhaust is a Greddy "Street Performance" cat back system. Don't know if this makes a difference with the smoke or not. Thanks everyone for any help you can give me.