There is no doubt that the 2010 GT500 will keep it up top as the king. I love that car .. just out of my price range. You have to take dyno results with a grain of salt. As we have seen on the LS3 Camaro, you could dyno stock anywhere from 350s to 370s (for an average and give or take for the oddball ones). That is a pretty wide variance to go for .. if you consider 16% loss on the manual, you would dyno around 358 at the wheels. So if you were one that dyno'd around 370, would that mean you actually made 440 at the crank? Maybe, but maybe it is just how that dyno reads.
I do know that my 4th gen SS was definately underated from the factory. They claimed 325 - 330 at the crank and bone stock I dyno'd 306 at the wheels .. either that drive train was really efficient or I had a hell of a lot more power
Crowley