My brother has (had) a Clifford alarm installed by a pro about 5-6 years ago or so. For the past year or so, he's been having fuel injection issues. The mechanics and the guy who installed his alarm said that the brains of his alarm unit were starting to die or malfunction. Apparently, the alarm prevents the gas from entering the engine. Sorry for the terms, I'm not really car-savvy. 🙂 Anyways, he had to pay the guy $50 to get the whole thing uninstalled from his car and has not had anymore issues.
I personally went with an AstroStart 5204 alarm/autostart system. It was cheap from my dealer and I wanted something to protect my stereo and car and to give me that reassuring feeling that everything is OK when I leave my car parked. I have about $2000 put into my stereo and would be very upset should anything happen. Anyways, I know this alarm isn't top of the line, but it works. There's no shock sensor, but if you bang on the windows, the alarm goes off. Also, it has all the other obvious things like door sensors, trunk, blinking light, and some other ones that I don't remember off the top of my head. A buddy of mine knows a guy who use to steal car stereos. He said if he ever saw a light in the car that would flash or light up at all, he wouldn't touch the car.
lastig21, did your stock alarm come with a blinking light? I'm just curious as to how ballsy your crooks were.