[rotorwrench]

Specialty car insurance is more based on agreed value as 41 LjH mentioned. Liability is generally a given but is usually more a fixed amount just like all other motor vehicles. If the policy is agreed value then that's all there would be. If you do work that increases the value, you have to change the policy for full coverage. You also have to follow the rules of the insurer as stated in the policy.

If you follow the rules and have an accident then it should be covered. If not, then litigation is the only recourse. If you increase your agreed value the policy will likely have a higher premium per period of coverage. It needs to be in writing to have a binding legal agreement. I wouldn't trust just calling them unless you know your rep personally and can trust them to expedite the changes.