The front area of the C6 is not only for cooling but downforce. A lot of research was done from the Corvette Racing team to redevelop the frontal area of the C6 (and luckily why we no longer have flip-up headlights).
I did this mod on my C4...just had John at AutoXTC custom make one for me.
Not sure if the C5 is the same, but you'll want to make sure the bumper is enclosed with what ever opening you make...other wise it will cause lift at high speeds.
This is the massive hole I cut, before boxing in the opening, therefore making sure the air goes straight into the engine bay versus throughout the bumper area.
