GM doesn't even make a factory forged engine like the gt500 has. I don't feel the current gen blocks are sufficient anymore. The 5.3 is getting pretty damn long in the tooth.
GM probably doesn't have an incentive to push the bar to new levels since the camaros and trucks are still selling really well.
The current Z06 has more performance than 99.9% of the drivers on the road can handle. That might have something to do with it also.
