Updating my earlier post, I am now looking at a NEW 2007. I can get the X-Plan at work, plus Ford is offering another $3500 on top of that on 2007 models. That means I can get a brand spanking new 'stang for $17500 - 18500 I have a list of 16 2007s on lots within 100 miles of my home. Now to choose.

Active anti theft. What more is is above the passive balring horn ?

"An optional active anti-theft package offers customers an added level of security. It includes a sensing module to guard against tow-away thefts, an interior motion sensor to detect smash-and-grab break-ins, a separate alarm sounder — in addition to the vehicle horn — to thwart thieves trying to disable the horn, and a high-capacity, 60-ampere-hour battery that sounds the alarm longer."

BTW, it does work. I have jacked up my Pony more than once in the garage while the alarm was on. It will go off!

Nothing that I know of. I think the only difference between active and passive is the shock sensor for windows/doors.

Well the passive is just that, the securi-lock key is the only real theft deterrent. The active has the actual alarm that sounds, the motion sensors in the overhead interior light housing, the extra horn, etc. When I bought mine, I thought it had an active system because the remote has the panic button.But no alarm sounds if you tamper with the car, or move it, or lock yourself in the car and "arm" it andtoss around in the back seat trying to make somethinghappen....

To the OP, if you want an actual alarm system installed from the factory, then get it.

i would get the anit theft system... i have it...and a few other deterrents which i dont discuss..... i think having a car of this caliber without an alarm in this day and age is not the way to go..... even if it was a new geo metro i might consider an alarm...but i also live in l.a. the car theif capital of the world .....

If you want and need the theft deterrant system, then go for it.
Most theives know how to defeat OEM alarms as they are all the
same from model to model and getting a doner to work out how
is easy for professionals.