I don't know if any special restrictions were applied to the cars.
Apparently they have lapped around 2-4 seconds faster than the v8 supercars, doing similar lap times to the top GT3 class cars which were also faster than v8 supercars.
Additionally Sports Sedans ( a type of unrestricted saloon class, think huge v8, superwide tyres and massive wings with a fiberglass body ) have been allowed to race at the venue after a 15 year absence, although I don't think they ended up going quicker than v8 supercar lap times.
I don't think there have been any safety upgrades, but could this relaxation of speed restrictions on the circuit open the way for classes such as DTM to fly out to race at the venue?
Edit: lap record @ 2:04.6 by Gilmour in an F3
Edited by V8 Fireworks, 09 April 2012 - 03:59.