Evo's dont come with an alarm system at all, just key-less entry and immobilizer. I can almost guarantee you that your evo will get stolen if you don't get a high end car alarm/security system depending on where you live. Trust me, you don't want to skimp on stuff like this. Its a small price to pay for peace of mind.
Take a look at these:
http://www.viper.com/ShopViperProduc...tegoryCode=102