Get the Viper Responder alarm. It's a high tech responding system that alerts you if your car is being tampered with. It's quite costly but trust me it's worth it. This alarm does so many neat things you wouldn't believe me until you see it. For example, one of the benefits that the alarm has is the transmitter. You're remote is like a computer with a LCD screen that shows a picture of your car. If you're car is being tampered with, a hammer shows up on your LCD remote and indicates a sensor 1 or sensor 2. Sensor 1 is an actual tamper sensor, sensor 2 is a motion detector. If someone hits your car, it ativates sensor 1 (Tamper). If someone is spying in or out your car and don't even have to touch it, it activate sensor 2 (Motion). You see all this on your remote with a range of up to half a mile. Man I think that is pretty neat. I also got it with the remote engine start. No more waiting for the car to warm up in the mornings. With the push of a button, I'm in the shower, getting ready for work and my car is ready to go. If you happen to forget that your car is on, no worries, it's programmed to turn off on it's own after so many mins. I'm set at 10 mins. I also got the modules that make the windows roll up & down also. On a hot day like today for example, with a push of a button I can roll my windows down so all the heat can get out while it's parked in the hot sun instead of going all the way to the car and roll them down. No worries about having anything stolen in the car because remember, it has the motion detector. I also have two kill switches. Knock on wood, but I think no one and I do mean no one can steal my car. Heck, I think the person that installed my alarm wouldn't be able to steal it if he wanted to. LOL. Sorry for a long reply but I thought that you should know.
Having a mustang is an VERY expensive investment, especially when you send all the money on mods and whatever else that we do to it. Why not protect our investment. It's the wise thing to do. The factory POS alarm that we have is like what I said, a P.O.S.