I saw this in another thread and thought I'd repeat it for everyone's benefit. I know alot of you already know this information, so forgive me for repeating....
The reason for the ass end of the vette is simple, and one I've heard repeated over and over. Mostly in articles from the engineers and wind tunnel guys.
Actually if you remember Cafaro's black car didn't have this abrubt 90 degree angle in the rear, and that's not the way he wanted it. However one of the critical goals that had to be met for the C5 was its aerodynamic slipperiness. To make a long story short, the wind tunnel and aero guys won this battle, you see, (I'm not an aero expert, just repeating) in order for a car (or any object) to demonstrate effective tunnel numbers air must cleanly enter the flow in the front of the car, travel relatively unimpeded over the surface, then make a clean exit off the rear.
This 90 degree angle was needed to reduce eddies and other stray currents when the airflow exited off the rear facia.
Short answer? Don't change your rear facia, unless it meets these requirements. And even then, ask for aero numbers...Unless you're all show and no go...or just want more flash than dash. /phpBB/images/smiles/icon_smile.gif
Feel free to step in and post your comments...or corrections....
The above information was gleaned from a taped interview I saw once with a GM engineer and from All Corvettes Are Red...
JC