Sa Banawe. Ohlsen is the name of the guy who installed the relays. I dont know where in banawe he works now but from time to time I still see him. And yup, relays lang kailangan mo, Ang laman ng modules eh basically relays din lang. The relays recieve the signals from the alarm modules electrical impulses and acts as a switch to other system. I dont know kung may viper 900 pa na available. Alam ko wala na. Viper 800ultra is almost the same except separate ang voice module, so walang silent mode lagisyang nagsasalita, maingay.