taken from another forum:
http://www.dragtimes.com/blog/2008-chevrolet-corvette-ls3-dyno-results
They took a 2008 LS3 Corvette and added:
-longtube headers
-performance cam
-ported intake
-K&N aircharger
-Underdrive pulley
-Custom tune

Result: 506rwhp and 457 lb/ft of torque.

This car will be the best performance bargain on the market when released.

This is also right after the competition wherein a normal LS2-powered Z51 base C6 whupped up on a 997 Turbo and an Audi R8 on VIR raceway:
http://www.caranddriver.com/features/13173/the-lightning-lap-2007.html