In a street driven application, you would have to work very hard to push a tuned GXP to turbo failure. I would be more concerned for the safety of the people around you. The amount of time that you could spend >6000 rpm and > 29 lbs./min. is just too limited in a street application. To be honest I dont see to many track applications where this would come into effect. You would have to spend time at WOT or very near ala NASCAR to put the car in this position. Now if we had an Autobahn.
My other turbo charged vehicle is a diesel truck and in heavy towing situations I run it at 1100*F and greater for hours on end, I have a fuel range of 600 miles. I do use a cool down technique when it has been working under continous loads, however it doesnt take but a few minutes to get the entire system way below safe temps.