I had the wire for the truck release disconnected and the actual key cylinder on the outside of the trunk was taken out and filled in. I bolted the sub box down so it could not be moved from the back seat making the only way into my trunk, the keyless entry (and I had two just in case).

Best thing to do to prevent a thief is to not let them know you have a stereo in the first place. Do not play your music in your neighborhood (mad neighbors are prime suspects .. LOL)

Any visual deterrent is better then nothing. If a thief second guesses himself .. he may think twice about it.

Park your car in a well-lit area. Motion detection lights are the best. Thief’s like the cover of night.

Park as close to the house as possible. Thief’s do not like the fact that someone can sneak up on them. they are the ones trying to do the sneaking.

Make your stereo heavy and awkward to carry .. I put weights in his sub box just to piss off anyone trying to steal it. I also put no edge on the box so you can't pick it up especially with the extra weight!

Take out the factory screws and miss-match the screw types around your subs and bolt it to the car. That way if they want it .. they have to piss around with a few types of screws to get your subs out .... piss around with bolt that holds the box down and then steal it... trust me, they don’t usually want to be around that long.

I put a personal alarm in the trunk. You know the ones that you use when you go walking at night? When the pin is pulled it squeals away and it's loud! This is mostly a paranoid thing .. so if they have a way around your car alarm .. they will never see it coming but they will surely hear it and hopefully so will you with enough time to chase them away with a shotgun in your hand

Anyways, this is my two cents. Take it for what it's worth.