As many have pointed out, it depends on the location, company, and probably the agent you get. When I spoke to my agent about coverage for my WJ, I asked about aftermarket pieces since I do have quite a bit of money invested into it. He told me to keep a thorough record of all the parts installed (aka receipts) and have them ready should I ever need to file a claim. He said while he couldn't guarantee everything would be reimbursed, that it would help reimburse some money back. I have USAA.