Bro,
My alarm system once it triggers will cut the fuel pump, injectors and fuel pump. Naturally the alarm will make noise so they will try to open the bonnet but there is a secret button to open. If they do manage to open the bonnet, there are two sirens - one is visible and another is in the body panel so unless they want to dismantle the car, there is no way the alarm is going silent.
In addition, should they tow the car, there is a seperate GSM unit tracing the car 24/7 hidden somewhere in the car - they will never find the unit. If that's not enough each time the car alarm goes off, it will SMS my phone and I can arm and shut-down the car using my mobile.
If I were to be carjacked, the moment the car revs over 2500rpm, you have to key in a code similar to morse code and if you don;t the car dies and alarm triggers.
All my cars have this alarm, slightly expensive but well worth the cost and piece of mind. Small price to pay considering the audio system and other mods. But so far my car has been very safe, Thank God for the UTK guarding my house