since I'm the only one who's interested in this, I found this reply from another forum:
The current BFYB test took lots of cars (including an SS and 220kW XR8) to Phillip Island. The two cars lapped the track within about 0.3 sec of each other and the XR8 was the one quicker. I'm very impressed as this is the first time in a long, long time that I've seen 'stock' XR8 lap quicker than the SS. Until this test the SS was usually good 1.0 - 1.5 secs quicker par lap (depending on the track). Looks like the cars are very evenly matched now on the track ... 0.3secs is so close that it could have gone either way.