The Brant alarms were all installed the same way , as per Subaru's demands. Each car came with it's own set of codes for each specific VIN and were of a random assignment. Saying you don't know who installs a system at your local audio shop only carries the same risk as the person(s) who installed your Brant systems when they came off the boat. Having been in and out of the industry since 1999, I am yet to come across an audio/security "apprentice" as has been worded somewhere in the thread. The Brant alarm itself, while not everybody's cup of tea, I have found to be quite a reliable system - with the only real issue I have found being the range you get to unlock the car - sometimes I find myself having to stand rather close to the car before it arms/disarms. The Brant keypad immobilisers are known for being troublesome. There is a replacement aftermarket keypad system available, only downside to it being that it doesn't come with an anti-hijack option.

If one were to insist on going aftermarket for the full alarm system, there are a number of systems available. Some of which can operate from the factory Subaru key (like your Brant does) as well as some that come with their own remote controls. The level of security doesn't change a hell of a lot, depending how many "bells/whistles" you feel you need in a car alarm. Autowatch as a brand no longer have their own supply branch in WA although they're still available to obtain; and while they are known for being a reliable system among the "cool crowd," it may be worth shopping around as there are other options available for various budgets that can still offer a great level of protection. I would advise against fitting your own system unless you are sufficiently experienced, to help avoid damaging BCMs etc; not to mention insurance purposes etc. From an installer's point of view, as well as being a life-long car enthusiast, it's not worth taking risks/shortcuts, especially when it comes to protecting your hard-earned pride & joy.