I see the can can of worm I'm about to open... but oh well... I currently work for Geico. Have for about 4 years now. The performance mods part, correct, we won't insure them and/or drop a vehicle with them. That being said, most auto insurers are the same. Remember, if you have a local agent they make commission on what you pay so telling you your mods are covered means they keep your money. I would get in writing from ANY company that sc/turbo, cam, heads, anything performance that you mod is covered. In most cases it won't be and all you'll have as proof is "but he/she told me..." Not saying all won't, just most. In most cases you'll have to get custom insurance to cover it. Just don't want to see any of you guys get hosed if something happens to your ride.