It was mentioned in the review below (at that same event) that each journalist had a 10 lap stint one after another but many would not do a cool down lap. Therefore, the three cars available suffered from brake fade and shudder. One car experienced complete brake fade and was taken out temporarily for repair.
There isn't a brade pad in the world that would take that abuse. However, OEM brake pads are not designed for track use so I would be willing to bet a pad upgrade would solve the fade problems for track use on stock tires. Maybe cooling ducts would be necessary on slicks.
http://blogs.km77.com/teletransporte/7899/toyota-gt-86/