i use to have a clifford (something basic just siren, auto door lock and remote start) and after my truck got broken into and they didnt even care about the alarm going off i went to viper... and had extra sirens installed inside the vehicle... lets just say that if you are in the truck when those sirens go off.. either your ears will bleed or you will get the hell out as fast as you can!
i forget what the actual name of the siren is, but its inside the truck, and LOUD!!!