We just finished our first 2010 Camaro SS L99, installed ARH LT headers w/ stock mufflers, Procharger P-1sc-1 with 8lbs and custom tuning with HP Tuners...the car baselined at 314rwhp and 331rwtq, after 472.6rwhp and 470rwtq. The drivetrain loss seems kind of high on these cars in comparison to the SRT automatics, most of those cars make about 370rwhp stock which is only about 15/16% loss compared to the 20/21% we saw on this car.
Heres a link to the dyno video, please ignore my verbal screwup on the baseline torque:
We said 9lbs on the vid, but after checking the text page on the dyno the car made 8lbs at the 6000rpm