In case you didn't see this.
The current 5.4 is rumored to grow to 5.8 using the now old mod motor, and a Corvette ZR1-style S/C is supoosed to replace the current S/C. The advertised horsepower rating is to swell to 620.
So what should be a competitive shootout with the ZL1 Camaro in 2012, unless Chevy adds a few tweaks, the GT500 will be scoring a knockout in 2013.
Oh, and some of the GT500's retro touches are rumored to be tamed down. Word is in preparation for a more modern design coming in 2014.
Patrick