Depends on a few things...
- State laws
- Insurance Company's policy
- Proof/documentation
It's best to get your agent on the phone.
You may have to declare the value to insure...
Edit: Fault may play a factor as well...
In case of theft, itemize the value and see how much more coverage you may need...
Plus, depending on the type of loss, buying back the car w/ mods might be an option.