The primary upgrades include an all-new asymmetrical F1 Supercar Generation 2 tire from Goodyear with a new tread compound that GM says is a huge improvement over previous factory rubber, offering solid performance when cold and maintaining grip even when worked hard for long periods. Progressive and predictable traction plus improved lateral and longitudinal grip make this modification the biggest single performance factor.
A revised two-mode exhaust system also improves performance and sound thanks to the addition of the X-pipe (replacing the H-pipe) from the ZR1. A new set of option packages also up the available equipment, with a CFZ carbon fiber package that offers a black-painted carbon fiber splitter, side rockers, and roof (which saves six pounds) plus a body-color ZR1-style rear spoiler. The Z07 performance package adds Brembo carbon ceramic brakes to the mix along with 20-spoke Competition Gray wheels in 19x10-inch (front) and 20x12-inch (rear) sizes, plus Michelin PS2 tires and magnetic selective ride control.
These upgrades match most of what the 2011 Z06 Carbon Limited Edition (pictured) gets as part of its standard package, and were previewed with that car's unveiling. The video below, taken during a presentation at the C6/C6 Corvette Bash goes into detail on how the upgrades benefit the car's performance.
All in all, it's a nice set of upgrades that offers a way to get more performance out of the Z06's already heady mix of power and handling without adding the expense of the ZR1's supercharged LS9. We'll have to wait until we can get behind the wheel of one to evaluate the real on-the-road benefit, but we'd expect the difference--particularly in the brakes and tires--to be noticeable.