The odds of this making 10hp (or even matching the stock or slightly modified setup) are small.
This might subjectively win in the looks dept, but is not likely a winner in any other way. Holden is making a bonnet with scoops for the '05 GTO to keep traditionalists in the US happy - there've been spy pictures of it over here - but the '05 Monaro won't have it, despite being beefed powerwise up to compete with the 360hp Ford V8s. I'm betting they're not functional.
Holden uses airtunnels incorporating dynos to develop their cars - none, not street or racing - use bonnet scoops.
Supercars at Australian Grand Prix
V8Supercar Specs