My friend has one and it sounds lovely I have been out in it and also driven it. Just a slight blip on the throttle and you know about it back end can be a bit twitchy in certain conditions.
Here's his spec
Vauxhall Monaro VXR
6.0 ltr V8 LS2 Engine
He has had this work done within the last couple of years.
Magnuson TVS2300 Supercharger
Wortec Headers & Hi-Flow Cats
Wortec Performance Exhaust with Switchable Backboxes (Quiet or Loud)
Pedders Extreme XA Coilovers
AP Racing Brakes, Front 6 Pot 363mm, Rear 4 Pot 342mm with Ferodo DS2500 Pads
Power & Torque
613bhp (485bhp at the wheels)
600ft lbs (475ft lbs at the wheels)
Here's a little clip from Germany