I installed an alarm in my van but didn't hook up the shake sensors. I can't
stand hearing alarms go off every time a Harley goes driving by. But never
underestimate the smarts of your common thief. I have a blinking LED on the dash
above the headlight switch in plain sight. Some thief was smart enough to
know not to open my door. He first tried jamming the hatch tumbler with no luck
getting in so he breaks out the wing window, rolls down the driver window and
crawls inside and climbs back out never setting off the alarm. All he got was a
bag with a 12v pump and tire changing gear inside. If he had succeeded in
getting the hatch open he would have set off the alarm. He did succeed in
destroying the lock tumbler. Instead of replacing the tumbler I installed a solenoid
that is operated from my alarm's key fob. A nice little addition.
 I have "big ideas" of installing IR motion sensors that turn on bright
lights that point out the glass in the direction of peering eyes or a strobe that
looks like a camera flash.   Having the same IR sensors turn on a 12V remote
camera system would be nice too. But I doubt if I'll ever get that far.
 In the end I think the biggest deterrents are a blinking light on the dash
and not having anything visible to steal.
gp
87   Syncro sortafalia