If you bought your C5 with either the standard suspension or the F45 suspension package, you can make some nifty improvements in ride and handling for not very much money.  Here's how: replace your front and rear sway bars with the Z51 (performance suspension) sway bars.  I don't know about the standard sway bars, but the F45 bar diameters are 0.915"  in front and 0.76" in the rear.  The Z51 bar diameters are 1.0" in front and 0.865 in the rear.  You will need the following GM part numbers:

• Front Bar.............10234745  $74.75
• Rear Bar .............10283945  $41.75
• Insulator (2).........10280526  $15.48
• Insulator (2).........10401553  $27.48