I think the Z/28 will be 10-12 seconds per lap faster than the ZL1. It's an incredible track where the power of the ZL1 will help it in spots -- but the gap may be even greater with the grip and brakes on the Z/28.
About that corner exit from the Karussell -- I suspect the Traction Control is off or in track mode, and that's a hell of a difficult corner for suspensions. It's not very fast, either, so it's easy to overpower the rears coming out. You're at the limit of any suspension, with full cornering load plus the compression of the banking, and it's easy to get into the throttle too much and too soon. It's incredibly hard to ease into the throttle as the suspension unloads, as you can see the straight ahead. The car is nearly straight but the suspension is still loaded, and when you exit right at the corner of the concrete, the pavement transitions from banked to flat. The car is lined up but still has to exit that transition before you can hammer it.
That's just my $.02 and I have driven that circuit. And no, I didn't stay in a Holiday Inn Express last night...
