Jason, I have had also had brake problems while at track events. I chalked it up to poor choices in brake pad compounds and excessive braking. I switched from Mintex A/F pads to the Mintex 1144 for an upcoming event (next weekend). I have also committed myself to braking less. At the very least, I'll just brake earlier with less force.
As for using brake ducts, unless your rotors are vented inwards I don't see them being much help (but something is better than nothing).
