I went out last night to roll with these guys while they raced. The cobra has the basic bolt ons with a pulley and the ZO6 has intake, catback, tune.
YouTube - 03 Cobra vs C5 ZO6
YouTube - 03 Cobra vs C5 ZO6
YouTube - 03 Cobra vs C5 ZO6
YouTube - 03 Cobra vs C5 ZO6