Yep! My installer own a G2 Legend so he hooked my Viper up to work with my OEM alarm, so my horn goes off. Sounds very unique from the other vipers. Lots of noise though . So, it can be done. It works with the remote when I disarm it.
it's really simple.
i've done it to my alarm on the outside and inside of the car.
here's a basic explanation.
you'll need the following:
-air horns 20-40 bux
-bosch relay 2 bux
-light signal flasher 2 bux
-16-18 guage wires 5 bux
1. first tap it into the power lead of the alarm siren and connect it to the relay.
2. attach the power output of the relay to one end of the flasher.
3. attach the other end of the flasher to the possitive end of the air horn compressor.
then u'r done.
here's the idea of this setup. when the alarm goes off, power is sent to the siren. this power will switch the relay on and feed power to the flasher. then the flasher will feed "blinking" power to the air horn compressor and you'll have the horns going on and off.
hope i wasn't too vague. i tried to keep it as simple as possible.
the flasher is a little device that's used to make the signal lights blink. basically, it just cuts power on and off.
i picked some up at the the local car wash here.
if you want, throw 15 bux into my paypal account and i'll buy them and assemble it for you so all you need to do is ground the proper wires and tap into the siren power lead. if not, i'll take some pictures of my setup and you can go to the and electronic store and match up the items.