Before DEI took over, Vipers were just average alarms. And since almost every guy and their mom had Viper or its variants on their car, they catered to the lowest common denominator. Not only that, if you yank the brain or a part of the Viper alarm system, you disable its features. So if I wanted to drive off with a spare key, I can do it by just yanking the alarm brain out. I hope you knew that. Not so on the Cliffords. The Cliffords must have a continuous circuit in order for you to disarm and start your engine: an added security in case someone finds your alarm brain and tries to yank it out. In other words, unless if there's a continuous circuit and an active "command" to disarm (via transmitter), the system will prevent the starter from engaging. Plus only the Clifford AvantGuard 4 has a remote starter kill you can put on the fuel pump for added security.

I had Viper before and kinda got upset after hearing how easy they can be defeated. Clifford alarms (at least before they got bought out by DEI) made car theft extra harder than Viper alarms. And you can ask any alarm retailer (that carried both) on this!