Can the shocks be upgraded over time? Yes they can.
We are working on a webpage that will allow you to send the shocks in for any service you require; rebuild, revalve, reconfigure, etc.
As per your Z06 reference, we have the following (per corner):
OE replacement: $250.00
HQ Coil Over (single adjust): $500.00
TQ Coil Over (triple adjust): $850.00
http://www.ridetech.com/store/muscle...ures_hash=V364