well since people want a cheep way to get air horns i decided to make something on how to put together a cheep horn kit.
Materials:
1)12v compressor
2)air tank(any size; the bigger the tank the longer the blast)
3)air horns with a 12v solenoid
4)air hose(the bigger the hose the louder the sound with less psi)
5)a pressure switch or a regular switch( to turn on and off the compressor
you can get a 12v compressor anywhere. i got mine from pepboys for 25$, you can get a portable air tank(20$ walmart) which will make things a little easier but there big and space consuming or you can get a air tank made for air ride etc for like 50$ off the internet. the best horns for the money are on ebay from a company called Siege Engineering Equipment(
eBay Store - train horn: air horn, siege, engineering ) get either the triple or quad trumpet ones with the **GMAX valve**.
Quick install description:
the the compressor has a quick connect hose with a shreader valve on the end of it. now if you get portable air tank you can connect that valve directly to it. now unscrew the other hose on it that you would fill the tires with and replace it with 1/4 inch air hose. that will screw directly in to it and connect the other side of the hose to the horns which the ones i found, you can screw the hose right in to it.
now for pics!
now for the install instructions:
1: find a place to mount the horns then take the 2 wires comming from the air valve on the horns and splice one wire in to the positive wire comming from your factory horn and ground the other wire.

2: find a place to mount the air tank and compressor. try to keep them close together. now with this if you want to use a smaller regular air tank with this compressor you have to get some air hose and cut it but make sure one end has the threads on it so you can screw it in the tank. with the other end heat it up with a lighter or heat gun so its soft and flexable and push it on to the end where the air comes out of the compressor then put a hose clamp on it(ghetto i know but it holds really well) now hook up the compressor to a 12v source you can just plug it in to a cig lighter if you want and splice the positive wire to a regular switch or a pressure switch.

3: run a air hose from the tank to the horns
4: turn on compressor let the tank fill up and wait and listen for leaks.
5: test the horns with a low psi or air pressure.
6: fill air tank up drive around and scare the crap out of people and enjoy

** if you want to add anything or have any questions let me know**