got me a viper 350V or something like that, 350 something, at bestbuy done for like 250. I didn't really trust a car audio shop, best buy is a big company so I chose them for my alarm only. Audio wise, nah.
those bulldog alarms seem really cheap, but actually they are pretty nice. they are like 50 bucks at auto zone or w/e, and they easily get the job done.
mine goes off when any voltage changes in the car (ex. when the handle is pulled and light goes on, or when any light changes in your car).
so really even if they broke into the trunk, when the light goes off, the alarm will go off, so it doesnt really matter.
also when hit harder than just a tap, it will go off. you can set sensitivity. also comes with a remote.
the bulldog im talking about is very easy to install. you just wire the red wire to a fuse, and then u screw the alarm into the car somehwere under the hood. just predrill the holes, and use self-tapping screws like you would for doing a ground. theres a ground wire u have to put on the alarm too, but thats the easiest part.
i had some instructions on how to install car alarms and they spelled it out pretty good but it looks really tedious and you have to be able to check wires and get relays for everywhere.
any form of alarm on a car with something you value (and when its car audio, cherish!) will benefit you, if u cant afford something like a viper with all the bells and whistles yet, go for that bulldog thing he was talken about.
I came up with a couple of ways to keep your car secure and locked. If your back seats fold down for a coupe or sedan, get twisted steel wire, bolt it on to a place on your trunk, and secure it down somewhere on the other end so they can't open your trunk. I think I'll give better examples when I do it myself with pictures, just been lazy. Its no alarm, but they can't get to the valuables :D.
the bulldogs have just a remote with arm, disarm, finder, and panic. not keyless entry.... but still good alarm. i dont see how any would get into my car without it going off. no matter what any opening of the car, a light will turn on, making the light go out. and when u set the sensitivity, i dont see someone breaking a window to get it, it goes off when someone taps it with ur foot.