As for your 8 sirens cntrylvr79, good attempt, but wouldnt 4 do the same thing, or even 2? and besides if they remove the power from a dozen sirens it wont make a sound. There are some things a car owner can do or have done that will be similar to the devices mentioned.. like ignition kill, and other kills like that for min. cost compared to a expensive alarm system.
The key is probably to customize the system for each vehicle, so that for the criminals it isnt so easy to jump in and know exactly where and how to circumvent the security. Best buy and Circuit City have very well known techniques for installation that thieves know just where and what to do. putting wireless kills, and extra sirens, and backup batteries, and sensors, and so on and so on will help, but in the end if the car gets towed, the car gets towed. maybe make it even more difficult by putting the boot on the wheel.. but at some point we have to say geeze enough is enough.. dont park or leave the vehicle in those risky situations, and see that insurance is ample for taking car of such a loss.