All the Perimeter (PLUS) module does since you already have Remote Start with the Lariat trim is it adds the (shock) sensor which can be adjusted for sensitivity.I have had the Perimeter Plus module installed for a while now. The remote start works fine...when I can get the fob button sequence right. I have never been able to trigger any shock or vibration alarms with it, though...no honks when the door handles are pulled without the fob nearby.