Originally Posted by VictorH
I have this same brake duct system on stock rotors, calipers and track pads. This is one of these items that's difficult to draw a conclusion. Like the OP states, it's probably helpful but hard to know without back to back testing under the same conditions. I've never had brake fade at VIR so ducting kit made no difference there. I've had brake fade at Road Atlanta and I still get it with the brake duct kit. Do I go longer before fade starts? I don't know. Do my pads last longer? Not that I can tell. The one thing I can say with a fair degree of certainty is that once I have fade (not just a little but good rippin' fade) that the recovery back to usable brakes is quicker with the ducting kit. So hard to tell how much it helps without data, but it does help, though in the stock brake form, it's certainly no cure for fade on certain tracks were fade is an issue.
It's interesting that VIR, a very fast track you get no fade, even stock with no ducts. Maybe BMW engineers really did know what they were doing for the street then with the brakes on this car.
I am nervous to even attempt stock brakes on the track with this car.