superdavid

I've wondered about the kill switch. I know if it was me going to steel a car that had all the components exposed like ours do, then I would just run some temporary wires under the hood to hot wire it. Everything you need is right there, no need to mess with key.
So it seems like everyone is in agreement that I need to get a half track to park next to my Mustang instead of getting an alarm.... now I just need to explain that to my wife haha....

Adrenolin

I've got a car tazer in our 67 when its parked. Any little sh|thead who jumps in gets hit with 50,000volts of hammer hitting pain! I smile everytime I activate it via remote.

Battery relocation to the trunk along with the Solenoid. Aside from the better balance it also makes the car more secure. Its much harder to get into the trunk to start the car then it is to pop to hood. Also makes it harder to cut/pull alarm wires.

Any alarm cheap or expensive will work. Most people today like the remote start in the colder climates. Note that just because the alarm comes with remote start doesn't mean you have to use it! Our alarm has remote start.. I just didn't hook it up. Don't install an alarm under the dash!

Electric fuel pump with a toggle switch placed somewhere. No fuel it cant be driven away. Well... you get about 50 feet as I found out

Battery Brain hooked up to the battery in the trunk. Allows you to shutdown power to the entire car via remote!

Switches.. there are toggle switches that are easily noticed. There are also pressure switches which can be hidden under the carpet, behind the steering wheel, under the dash pad or even in the seat. These you casually touch when getting in/out of the car. Much better than toggle switches for a 'hidden' switch.

..I've even seen super thin and clear sensors that can be applied to the cars body and not easily seen. They were on some site to activate door poppers when shaving the door handles. These could be hidden damn near anywhere in/out of the car as a kill switch.

Modify any stock switch in the car as a kill switch. Who would think of turning on the wipers or fog lights before starting the car.

A buddy of mine has a stereo head unit with constant power from the battery. This HU has a button to automatically turn on/off power to the amps in the trunk. He instead used this button as a power interrupt for the car's ignition system and wired in a separate switch for the amps.

Lo-Jack! It's radio based, not GPS so it can be tracked even if parked in a container, garage, etc. Opt for the paging system and your notified if someone attempts to start or move the car.

ALL these things are great however they only stop the kids who want a joyride or the novice thief. If a professional thief wants your car he'll get it. Lo-Jack is about the only thing here that can help in recovery before it's too late.