Oh right, what do you mean by IPC here? If you mean instructions per cycle then you are terribly wrong, the only thing they can alter on a chip that already is made is the memory and core clocks.
What "more" is to them than older GPUs? What? TrueAudio is only on the new GPUs i.e. 260x, 290x [and 290, as well]. What else could they possibly add to the rebadged chips?