Originally Posted by DHL

Most insurance companies will not cover mods unless you buy assigned value insurance which covers the added cost of mods. They also don't like mods because it can push the performance of the vehicle above "stock" which is the configuration their actuarial tables are listed for. Case in point, in the 80's I had a BMW M635 which was gray market and was substantially higher performance (power, top speed) than the US 635i being sold in the States. The insurance company did not have the "M635i" listed in their tables, so they did not want to insure the car. My agent finally convinced the home office to insure the car as a plain 635, but I wonder if the company would have paid for the higher value of the M car if it was totaled.