If you don't report the mods they're not isnured and you don't get "paid" for them if the car is stolen or it's totalled. If you do too many performance mods to a "crappy" car the company will catch on. I work for GEICO and they're on a huge anit-street racing kick. If you come it and have mods we'll take note of them. They don't explicity raise your rates, but they're on file and if yuo ahve a mysterious single car accident we'll know somthings up. Too many times people wreck at teh track or street racing and say , "Gee I was just driving and lost it, or gee I hit a deer" The insurance companies are taking notice.

Modding an import or small car is a red flag. If I put a TT 427 in my car they wouldn't care.... it's the racial profiling of insurance. Young males modifying lower end cars are causing the most losses.

I'd report it just so it's covered. It may raise your rates because you are effectively increasing the value of the car.