What a coincedence!! I was looking into LoJack myself. I have a brochure and here are the different systems:
System 1: LoJack retrieve, Stolen vehicle recovery sytem operated by police. The LoJack unit is a small transmitter that is activated by a routine police theft report. The lojack signal can lead police directly to your vehicle.
System 2:LoJack retrieve and prevent starter diasbler, LoJack prevent is a passive starter disabler that deters a joyrider from starting your vehicle. But, if a professional steals your car, LoJack retrieve will allow police to track an recover it quickly.
System 3: LoJack Retrieve and alert alarm, LoJack alert is a remote anti-theft alarm that automatically arms itself an deters amateur thieves from starting your vehicle. But, if a professional thief steals your car, LoJack retrieve will allow police to track and recover it quickly. Alert features include: starter disabler, LED light, remote disarming, passive arming, panic feature, audible siren, valet feature, automatic reset, and 2 transmitters.
System 4: LoJack retrieve and alert alarm with keyless door locking/unlocking, this top of the line system includes all of the features of LoJack's System 3, plus it enables you to lock and unluck your power door locks several feet away from your vehicle, with the simple push of a hand-held transmitter button.
Sorry this was so long. I copied it from the LoJack brouchure. I work for a dealership that would install the Sytem 1 for 305 dollars. Install would take about 10 mins.! I have keyless entry and since it's a 97, it already has a coded key/immobilizer system. This is about all I would want done to the car. I'm leary about anyone getting into the wiring and messing something up if you know what I mean. (I have nothing to do with LoJack) Just passing on some info and hope to be helpfull. John