I was basically brainstorming about alarm systems, and I decided to go with the Matrix rs3. Ok, here's my idea. If a person were to buy a battery backup siren, on top of the normal siren, would it be a bad idea to mount it inside the car? I'm curious if the glass would shatter or anything. In my opinion, if a thief were to break into your car, and cut the wires and stuff, the backup siren would keep going. The beauty of it is, you can't plug your ears and work at the same time. I think 128 decibels on the inside of the car would deter most thieves from unmounting your deck. If the thief opened the doors to let the sound escape, people would hear it even more. With the doors closed and windows up, the sound would have to be unbearable. I'd probably mount the siren in a hidden solid fashion, so it couldn't be just grabbed and chucked. The only downfall would be a false alarm while driving, could cause an accident. Input would be great, and comment all you like.