adding a siren to factory alarm?

i was wondering if there was any way i could possibly wire in an aftermarket alarm siren into my factory alarm on '07 durango? i basically want to try and do away with the horn honk i get now when i arm it. it  already has the factory remote start and all which is why i didnt want to go out and buy/install a whole new system. and it will also honk the horn twice when i remote start it, which id like to change too. any ideas?

cool, thx for leading me in the right direction. any ideas on adding a siren as mentioned?

A relay, cut the wire that now goes to the horn. Horn wire to terminal 87, vehicle side of horn wire to terminal 30. Siren power wire to terminal 87A. Ground to terminal 85. Switched power to terminal 86. When your truck is powered up, the horn will blow. When the ignition is off, the siren will sound. You can not get the dealership to disable horn honk if you want to use the above.

ok great, so it is possible to do then. i figured on the horn wire being cut, id have no horn at all once i put the siren in place. so now my question is, you say when the truck ignition off, the siren will be the only thing(chirp and no horn)? also, would you happen to have any wiring info on this by chance? thx in advance.

Yes, when the key is off the only chirp you will hear is the siren.  The only drawback is, if you are sitting in your truck with the key off, and press your horn, you will only hear the siren. 

Wiring info:  Find the horn, there is going to be only one wire going to it,  that is the wire you cut.

Is there a cigarette lighter that gets hot only when the key is on?  If so, the center wire of that socket will be a good place to get switched power.

ok thanx for your input. one other thing. i have an LED scanner from a previous alarm. they way i have it wired in now is when the ignition is off, its on and when ignition on its off. any way you can think of that it will only come on when i actually arm the vehicle? if i remember right, on the old truck, it was hooked up to a negative out when armed.

The only way to make that happen is going to be with a magnet mounted to your lock mechanism and a reed switch mounted to the car.  You will have to mount the switch so it only makes contact when the vehicle is locked.  That is the best I can do for you.

hmmm, no idea on how to go about doing that mod?

Remove a door panel and see if there is a linkage or some part that moves wen the door is locked and unlocked. You have to attach a magnet to that part of the mechanism. Then you will need to attach a magnetic alarm switch or reed switch so that it is activated by the magnet when the door is locked.