honestly auto-x is kind of taxing on your brakes, but the top speed I could ever expect to see is maybe 85km/h on the slalom section... fade is not an issue here. stock slotted rotors with half decent pads would work just fine.
its in road course racing where big brakes really shine.. also think that by the time you have decided to go nuts on brakes, you are probably a track whore and try and fit in laps wherever you can and you probably already own racing tires that have much much higher traction limits then street tires do and therefore can actually take advantage of the huge amount of braking force your brakes can generate.

1995 Eagle Talon ESi