if you didnt report your new stereo/speakers/amps/subs to your insurer, then your going to have a problem. the only issue (to my knowledge) is if you do have an accident and youre want 2 claim your stereo, you just gotta prove you paid $XXX amount for your stuff (ie- recipts that match the amount you reported to pay for the system) to the insurance company. then i think there is the other issue of how old the car/stereo is.. (once again not sure bout car insurance specifically but im pretty sure with home contents insurance this applies - check with your insurer) that even if you bought your stereo new, they will only pay back the value of the system depending on how old it was.. so if youve your sub got destroyed in an accident and you bought it for $200 5 years ago, then they will only give you enough money to buy a 5 year old sub. i may be wrong about that but im sure that applied somewhere in 1 of the insurances ive got?!? probebly the home contents insurance... not sure! as for if your insurance would be void... i dotn think that would happen with a stereo thing... to my knowledge... if your car was in an accident (ie - crashed into a tree) and they found the cause was some faulty aftermarket breaks that you DIDNT to tell the insurer you had fitted, THEN they wouldnt pay up. according to them... your insurance wouldnt cover it cos you didnt report it (the aftermarket breaks). as long as all the stuff in your car is listed in your insurance policy youll be right. - thats wat AAMI operator told me. if it was your fault or not, wont matter... they insurance company should pay, but your premium will have to increase afterwards.. theres the catch once again dont quote me on this! i dont work for your insurance company!