The car already has an immobiliser so why do you want to fit another?
This might also be an issue with insurance so best to check that out first.
I think it's the thought of the key cloning. But then again a tin box has the same effect, for far less.The Autowatch Ghost Immobiliser II by Autowatch is a revolutionary immobilisation to secure your vehicle. The system protects your vehicle from key-cloning, key theft and hacking through a unique pin code that you choose to protect your vehicle. Essentially the only way someone can take your vehicle with the system is to actually tow it away and they still wouldn't be able to drive the vehicle.