Viper Alarm

They all seem to work that way from what I've seen - it doesn't seem to make sense until you realize that you can't drive it if the brake switch is hooked up

Here's the diagram I tried to attach before - this will give you a shutdown if either the alarm is triggered or if the brake switch is closed.

It's good to have both to have a simple quick way to kill the motor w/o having to trigger the alarm or turn on then off the ignition. You can still substitute your parking brake (or some other kill switch) if you like I guess.

Incientally, from your opening post, it won't reduce your siren amplitude.