[drunkenup]

At advanced pace a driver in a tuned, stock radiator/oil cooler n54 can hit temp thresholds for limp mode within a few laps if ambient temp is upwards of 80 degrees. On a 90 degree day, you'll overheat the car SEVERAL times during a 20 minute session if traffic is light.

If its 60-70 degrees out you can probably make it through most of a session.

I second the suggestion davidwarren made. Keeping water temps down will help avoid knock. The smaller 5/7 inch FMICs aren't very effective at keeping IATs down on track so you may want one of the 7.5"ers. Also be sure that your car is happy with the tune its running, and iron out any big timing corrections