idk about that.... damage to your property by someone else's negligence should be covered under their insurance policy. Its their responsibility to make you whole again. If they bend your wheel then they have to replace it. If you have property in the vehicle that gets damaged they have to replace or pay to fix it.

example. I used to be a musician for a living and I got smashed by a young teenage girl who didn't stop at a red light and plowed me pretty badly. This resulted in damage to some sound equipment and my amp getting pretty messed up. Her insurance company paid for both replacement and repair costs for me. I did have to prove that it was in working order prior to the accident, which was easy because I had just left the gig that I was using it all at. I would imagine your custom exhaust, coilovers, or custom wheels would be covered just the same. Its their responsibility to get you back to where you were before the accident happened.

I however do not work in the insurance business, so if someone is of more knowledge on the topic feel free to correct me.

He/the shop should have liability insurance which covers damages the shop is liable for.

I've got $5000 of aftermarket insurance through Elephant insurance. They didn't even care what the mods were.

Just had a chat with USAA. I have 15k+ in mods and told them the issue. They cover up to $5000 in mods in any given accident. So if I damage 6k in mods in a front end collision they'll cover 5k. If the car is totaled I am allowed to remove parts from the car but they will take that into consideration when writing me a check for the car itself. They don't charge extra for the 5k in coverage but they won't provide more with a larger premium. They recommend going to a local insurance place that will evaluate the car in person and get it covered for a certain value that depreciates over time.

What insurance company?

There's a golf course near here that costs 80,000 a year just to play there.

USAA

I switched for this specific reason. Esurance will insure up to 4k. You can purchase additional insurance outside (which I did)