I spent quite a bit of time at Sema this year, and a lot of time talking to critical GM engineers for the new G8. Here is a photo link I am working on that shows the G8, and a lot of upgrade info on how to make the G8 handle like it should for those who are performance oriented.
Early in pre-production there were some indications that portions of teh front suspension required mosification to comply with curb contact in teh US. Also, several thousands of miles of tuning miles were used to give the G8 its own ride and feel. An interesting comparison would be back to back on track testing of both the G8GT and the Commodore SSV. I know one or more of the mags flew to Oz and tested the Holden version there, but they only reported numbers as repoted by Aussie magazines.