Music seems to fit the car and vid if you ask me. Numbers sound right to me my buddys CTS-V with a stick made 480rwhp stock and 560rwhp with pulley, tune , intake , exhaust but still has stock manifolds. Not sure about them making 600rwhp with pulley and tune. Also if you think a GT500 heat soaks fast with a pulley the ZL1 & CTS-V are good for a few pulls then its cool down time.
With the numbers Livernois has reported on CTS-V projects they are going to need a cam to hit 600whp. Head and Cam with intercooler upgrades netted them 660whp. That is probably enough to satisfy most people.
Numbers probably won't get interesting until ZR1's 2.3 starts getting bolted on ZL1's.