With you going from the stock airbox to an open element K&N, I'm betting it will lean out your A/F ever so slightly. You'll pick up a decent amount of HP too! I'd still throw your car on the dyno as soon as you can though just too make sure it didn't lean out too much.... better safe than sorry... It won't mess up the tune, but a plug that's too cold or too hot can cause problems by itself. I had more trouble with the NGK TR-6's when I installed them. Come to find out they were too hot! I went back to the stock plugs and haven't had any problems since. I've read that the Denso's are causing problems on the SC'd high boost cars lately. Seems they've had a rash of Denso plugs where the insulator at the tip cracked and was consumed by the motor. No, but it sure can affect the way the car runs! I'm really surprised a CAI wasn't one of your first mods! You are one of the only people I know with a 2.8 and still running a stock airbox! U.M.