Looking at the last 3 pad types I've used, all have an operating range up to 750degrees. Those PMU ones Mike's looking at go up to 820degrees.
I'd suggest those 4-2s are not sufficient for the weight of the car and the temps seen on track. DS2500's fall off a cliff at 550degrees. Seeing a link?? I'm sure these are fine on a 106 Rallye, or something with really good cooling, so it's really not the pad's fault.
It's a heavy car, capable of high speed and does all of its braking with the fronts. You need some serious ducting and crossing of your fingers, or get something better suited.
I'd also suggest they've not been bedded aggressively enough and they've sh*t their resin out all over your discs in the process.