Went to the track last month and after about 4 hours of hard driving the car started sputtering just a bit. 5 minutes later it through a CEL and the code read missfire in cylinder 3.

After cooling off, the car started running fine. 1 hour later, after another session the same thing happened and I called it a day. I didn't want anything messing up. On the drive home car ran great and eventually cleared the CEL light on its own.

Never really had a major loss in power. Car rides perfect now but looking to go to the track this weekend and don't want anything screwing up.

Things to note:

1. car has 15% pully on stock software
2. exhaust tips were chalky white, so I assume it was running lean.

 

First I would sea-foam the motor to get rid of any carbon that could be getting hot, and causing the misfires. Next I would look into why the car is running a bit lean... Are the tips white or gray? Did it return after you wiped off the tips? Maybe you are just running lean at high rpm's, I know it happens on 17's, so it could happen with 15's.
Personaly, I would check the injectors, fuel preasure, etc. Perhaps something is just a bit out of spec, and in daily driving it is ok, but when stressed to the max, it cannot keep up, resulting in a lean condition.

 

Daily driven the car runs perfect. The exhaust tips have always been black but only at the track did I notice them to get chalky white.

93k miles and I've got a book full of service records to go with it.