Hey being an active rally driver like Bryce above, I'll also chime in.

Facility insurance is the way to go not because of increased coverage but because of the transparency of the whole deal. My rally car is insured as it sits as a race car.

They will require an official appraisal from a registered/licensed appraiser which is around $200. This will document the car in multiple photos with all modifications included. That package will then get sent to your company as well as to yourself.

Then they will charge you roughly twice what you pay for your street car assuming you have zero tickets/violations. For myself personally I pay somewhat less than double.

There's no other way to guarantee insurance coverage in the result of an incident on transit. Otherwise you run the risk of them showing up and saying well this is a race car and this is not the car we insured based on what was disclosed to us. As for what it would do to the sport...that's another discussion.

That's my understanding of it at least. I've been rallying guilt free from the get go and plan to keep it that way.