Anti-Theft Siren

Many cars have a siren mounted so as to announce to the World somebody is Stealing or Messing About with your car. Most people Ignore them, as False alarms are the main thing these devices announce. So... My idea is this: Mount the Siren (120db or louder) INSIDE the car. The firewall under the dash is good, so is the package shelf [perhaps as part of the 3rd brake light]. How it Works: The Goblin forces entry into the car, tripping the System. It waits maybe 20-30 seconds, then sounds a warning "burp". At the end of the wait, it Locks the car doors and lets the Siren go for about 20 seconds. It then un-locks the doors and gives the now sonically ten- derized thief have a chance to get out. Then, it re-locks, gives another 20 second blast, and starts blinking the car's lights to announce it has a trapped Goblin onboard, and would the Police please pick up whatever is left.