Welp, if you open the trunk, open a door (inside or out) or open the hood. It will set off the alarm until you put the key in the ignition.
Now I have a '93 ES, so keep in mind I don't have 20 grand to loose, but to me the factory system is good enough if you don't have thousands of dollars of things laying in your car to be stolen. (I have some money in the stereo, but you couldn't actually take it out easily so, I don't really care!)