i had those, and my gtp would get sketchy from some high speed stops some times... granted it's a heavy fucking turd of a car that shouldn't be going as fast as it was to begin with.
i went to these though:
http://www.amazon.com/dp/B000COCNCW/?tag=tcg21-20
and it was a significant upgrade to me, the fade isn't there like the other ones had, but again, single piston, 12" rotor, junk brakes.