[jhv48]

Classic Vette versus home built Cobra?
Apples to oranges.
I agree that every insurance company rates each vehicle differently. Rates are a result of the history of claims for the vehicle (potential exposure), the driving experience of the driver and his driving record and insurance company reserves. Insurance companies are required to retain billions of dollars in reserve to pay future claims. When companies lower rates due to lower than expected claims costs, they attract new customers and ultimately their exposure, read that claims, increase resulting in them raising premiums to rebuild their reserves. The thing to do is SHOP AROUND! Try to find a company that is trying to attract new customers with reduced rates. But don't be surprised when they raise your rates in a year or so due to the increased number and severity of claims that they incur from the new customers. This is the nature of the insurance cycle.
To tell you the truth, how many of us would put up millions of dollars to insure a vehicle that some guy put together in his garage with all the wrong tools and used parts he pulled out of a junked mustang? No quality control, no supervision, no inspections. How do I know that he didn't put the shock on upside down, forget to tighten down the control arm, leave the lug nuts finger tightened, use a shock that is about to fail? But I'm supposed to ASSUME he did EVERYTHING right and then put a rocket engine into it and is going to drive it like a dragster. You should get on your knees and thank God someone is willing to back your build with their billions of $$$.
If I was us, and I am, I would shut the f--k up and fly under the radar to the best of my ability and pay my insurance company and be thankful that I can even get insurance on these beasts. Each and every one of us is just one mistake from driving off a cliff, or spinning donuts in the middle of the freeway. We know what these monsters can do. The insurance companies don't.
Stop poking the bear with a stick!
We may find that whatever adjustments they make may just exclude us completely. Remember, they don't need our business, and they don't HAVE TO insure us! These things are never stolen, but they are often crashed, resulting in thousands of dollars in repairs unless another party is involved, then possibly millions. Most companies accommodate these rockets as a convenience to their loyal clients that have multiple policies with them. I have all my policies with State farm and they insure my Cobra for $630/ year with the same coverages as my three other cars. No mileage restriction, and a stated value of $40K. Am I happy? You bet!
Pay your premium and try not to kill yourself. The more accidents we get in, the more red flags go up until finally they wake up and realize that they are insuring guided missles with wheels and mostly inexperienced pilots. Guess what happens next! EXCLUSION!