[Aussie Mike]

I just bought an imobiliser for mine and I'm plumbing it directly into the wiring loom as I wire it up. I figure it'll make it harder to work out which wires to cut to get the thing going. The imobiliser I bougt uses a small electronic key you touch to a socket in the dash. It has two sets of relay contacts so you can disable the fuel pump and the ECU supply feeds.

It has a hotwire feature that if it detects someone trying to hotwire it ie ignition goes on without disabling it then it sounds the horn. Only cost $100 too.

I figured an alarm was a bit of a waste of time for a car with no locks and no roof.

Cheers