JC_451
Autocross Champion
I remember reading a couple of anecdotes about people who track the car(modded mk. 7s) pushing towards overheat coolant temps and the reasons people gave to explain it was that a FMIC blocks air flow over the radiator.A Few threads mention either the AC having to work harder, or not blowing as cool, some claim higher coolants. Though I've never seen any of these complaints coming from someone with a FMIC.. just being made.
A factory mount IC performs better at the track I would assume, but that's pure conjecture.