If you are buying new, then the tracker will be fitted at Reading if you ask your OPC to do it (where all imports arrive for their pre-delivery inspection). This is fitted by Porsche people, so they have some clue about how to take the car apart and put it together again without trim damage, etc.
They charge you only about £10 more than getting tracker people to do it. Worth the peace of mind, IMO.
If it is not new, I' m not sure what happens, ask the OPC.
They only fit tracker, www.tracker-network.co.uk. Click on stolen vehicle tracking for cars, then on private cars. On the right you will see the product options and pricing.
There are three options, Retrieve, Monitor, Horizon.
I believe the RAC Trackstar s the same thing, resold by the RAC, so they rename the 3 options, but they do the same thing.
Navtak is a similar thing.
http://corporate.itisholdings.com/navtrak/
The main options are based around how the system gets activated.
Basically either you notice it is missing and call them (not so good if you are away on holiday or on a business trip), or the car tells them itself when it is being moved.
It can tell because either it is being moved without the key (Tracker approach) or the transponder is not in the car (Navtrak approach, covers car jacking but means you have to carry additional peice of plastic with you everywhere).
Both will cover hotwiring, but this is unlikely with cat 1 3 circuit immoboliser, or it it is on the back of a trailer.
The top of the range systems have a GPS system built in that transmits its location when it is starting to be moved. Therefore the police know exactly where to start looking.
The tracker people beam a signal to the unit to turn on its radio transmitter. All police cars (and helicopters I think) can receive this. This is how they find it. This will (alledgedly) allow them to find it even if it is under a railway arch, in a multstorey car park or in a container or lockup.
Obviously the sooner you know it has gone, the smaller the search radius, plus getting the GPS coordinates from the unit helps.
The Navtrak one uses GSM to phone its location, so works on the continent as well. This would have to fitted by them, rather than Porsche.
Have a look at the options.
All depend on you though, since they will call you to make sure it is not a false alarm. Then you call the police. They will then liaise with the police.
Car theives have now started parking the cars only a few miles away (so they are not in them for long) and then waiting to see if the police arrive. That way they know there is a tracker. There are many places to hide one in the car, so they can' t really check for them. Until activated they are passive, so you can' t detect them electronically beforehand.
My car lives on the road, so I had to have one and went for the Horizon. The insurance company was quite pleased and I got a pretty reasonable quote.
For Tracker, the boxes are made by Motorola and have a life expectancy of 10 years. They cannot be transferred between vehicles. Under their pricing options, it is cheaper to pay the fitment fee and annual fee is you have the car for less than 3 years, otherwise pay a one off upfront fee.
Hope this helps.
Rgds, Stuart.