ohh yeah forgot to mention.. another good idea is to hook up teh horns to an AUX output on ur alarm.. it is hilarious.. we install trainhorns at my work usually at least a couple a month.. and scaring the shit out of ppl never gets boring.. and being able to sit back at a bar or sumthin and have ur car parked in front of a sidewalk.. and when sumone walks by hit the button on your remote... is priceless.. what i woudl recommend as far as hooking it up to the regular horn button is to put a switch in between it so that if u do get pulled over.. u flip the switch.. push ur horn button.. and its still factory..
and if u do u do hook it up to AUX and horn output rememmeber those are NEGATIVE outputs on the alarm.. so you'll need to build a polarity change relay to make them positive before they get to the horn solenoids.
one last thing.. the horns are LOUD regardless.. but they are directional.. if u have them facing a certain direction their MUCH louder..