that may be true, but so are the c6z06's. I've seen in person a stock c6z06 dyno at 486rwhp. I don't think its only losing 19hp through the drivetrain.
*edit to add*
I used to trap 105mph then I added 100shot of nitrous and was trapping 114mph, took that off and went procharger and now trap 120+mph. In this range of the 1/4mile it's not as hard to pick up MPH.
Thats the highest i've heard of a c6z06 dynoing. usually in the 44x rwhp range.
http://forums.corvetteforum.com/showthread.php?t=1940271&highlight=SAE