newbee to precision pro alarm

I am installing a Scytek Precision pro 500 alarm on my Mitsubishi Galant, 2001; I had done some basic alarm install before, and I need to do this myself (for finantial reasons) but this system is more complicated than I expected; I hope I can find the knowledge here. this system is a remote start/alarm, it have 4 set of wire plugs, I already connect the most of them, except for the remote start set which I plan to get to this weekend. The first question I have is: the system, arm itself, even when I start the car, why is this? Also, the alarm have one wire for Tach input, another for a Oil pressure switch input; neither are connected for now, I guess they were for the remote start funtion, but, now I dont know. thanks in advance for any help or explanation about this.

If you hook up the ignition wire it will stop arming itself with the ignition on. How do you expect the unit to work correctly half hooked up? Just use the tach input, don't use the oil pressure switch input.