i sprung for the Z-51 package that includes larger tires and a more suspension goodies. Although the suspension is most impressive, the active handling system is very protective. If you are a novice, it will protect you from driving beyond your limits. That said, I have not had it on the track to see what happens when I turn off the AHS. Spinning the tires with the AHS and traction control on is very difficult. If you turn off the traction control and AHS, you can light em up all day long.
GM should include a 6 disc player with the DVD navigation system. A single CD seems a little chincy