i agree with the lowjack recommendation and keep in mind some viper alarms have GPS. but, a fuel cutoff can be effective it done correctly. correctly meaning that you don't get the wires to the pump from under the seat, but somewhere else(under the dash, at the ecu) and make sure all the wiring is soldered and all the factory wire loom looks factory after your done. as for the immobilizer, that only stops the unexperienced thief.