I have the Autowatch Ghost fitted to mine and its worked flawlessly. Irrespective of whether thieves bypass the OBD or have the keys, without the code which is inputted by a series of self selected/programmed button presses, the car won't start.
Mind you, still didn't stop someone from having a crack at breaking into my house for the keys recently.
Also use a disklok following that when parked overnight or for any length of time.