If you already did the fuel kill and the ignition kill, then adding this to your car could be considered redundant. It's up to you.
There are advantages to this method over the Plug-In, Engine Bay Ignition Kill. This method is built entirely from electronics store parts so there's no need to scour the junkyards. This method is easier to put together for the beginner. Unfortunately, there is one glaring problem with this method on manual transmission cars. You can still push start the car. So I strongly recommend that you use this method in conjunction with the fuel kill. The disadvantage to the fuel and ignition kills is that you can burn up your starter cranking it too long if you forget about them. Oh well, you shouldn't be driving drunk anyway.
Like the Ignition Bay Start Kill, this strategy is plug n play, it can be prepared in advance, it's easily reversible, and it doesn't require any cutting of your factory wiring.
Pull this connector off the starter and re-route it towards where you will be mounting your relay. Extend this wire by crimping a male spade connector on some 10 gauge wire and connecting it to the starter wire. Tape the connection. Wire the relay as shown in the diagram below.
If you've been following along this site, you should be very comfortable with relays by now. If not, go look at the fuel and ignition kill pages. This is exactly the same thing, just a different way of connecting to the wire without having to cut it. As usual, you can connect the relay to your alarm's ground-when-armed output, or you could wire it to a manual switch.
This is the final result. Just make it as inconspicuous as possible.
