I used to have a Clifford Concept 60 on a previous Pug 306 S16 and it was great. It to had BlackJax and was a handy thing to have, except when you forgot about it
Basically the system, as mentioned above allows you to just step out the car and let the carjacker get in & drive off.
The system them looks for a brake input (it's wired into the brake light switch) before it starts to activate the BlackJax and if the code has not been keyed into the alarm via the valet switch the system then starts counting down.
In this time the brake lights flash, to warn motorists behind the car will stop soon and the valet light inside the car will flash to signal a response like inputting the valet code. If no code is input then the ignition supply is cut by the alarms relays, the alarm goes off, the windows roll up (if total closure is fitted) and thief panics and legs it.
Legit driver gets in, inputs code and alarm stops sounding and away you go after him in your VTEC
It's not an instantanious trigger, it does wait a while to put a safe distance between you and your car.
Personally I'd suggest a Clifford, as there is so much you can do with one and their prices have come down in recent years.
Some have had problems with them, but as with any alarm a lot of the issues come down to poor installation. Choose a good installer and your away.
At the time I had mine I had good friends in the trade who gave me the installation instructions which were a big help and I fitted it to the S16 myself, after ripping it out of the 1.4 Pug previous.
Must have add-on is the 2 stage perimeter system, "Warning! Alarm will sound if you dont back away!" heard that in your travels? It was most probably a Clifford, first warning of 2 before alarm sounds if someone is lingering around the outside of your car for too long.