Mike,
I agree that you will never fade stock Supra brakes on the street. Toyota did their homework and gave us a badass braking system.
But you don't have to have a gutted 600hp race car to fade them on the track. Some of us drive these cars as god intended, and take them to driving schools / lapping days occasionally. I can pretty easily fade stock brakes on the road course. I have to run an insanely aggressive pad (Hawk Blue) in front to prevent fade, which makes me have to buy rotors every 6 months or so. Luckily the rotors are as cheap as the pads (heh).
If I had 18" wheels to be able to fit the big AP brakes, I would get them in a heartbeat.
Andi