I pieced mine together. I bought and burned up a Harbor Freight compressor due to me using sound as my "pressure switch" I was too cheap to get a proper pressure switch and relay and it cost me that $50. So i upgraded to a Viair 380 with a 165-200 pressure switch(http://myworld.ebay.com/arnott_air_suspension
). I got my horns from Siege Engineering (http://myworld.ebay.com/siegeengineering
). They have rocked and helped me so much choosing my stuff. Very good customer service and excellent products for reasonable price. I got the Kong horns and was going to mount them where my spare tire was under my Sonoma when I had it (pre Feb 2007) and then revised my ides when I got my ranger. I took the horns off of the base they came on and then ran 3/8" line to each horn from a 3-way after the solenoid. Each of my trumpets occupies a corner of the truck, under the bed. I did not put a trumpet in the corner with the gas filler tube, but instead used the other 3. I had some scrap 2" square tubing that street signs come on and used those for scrap mounting paces. Two trumpets went behind each tail light with plenty of room to work and the longest trumpet was mounted ot the bottom of the stake pocket on the front, passenger's side. This was before horns got so popular and becoming more accepted. I was fearful of getting pulled over if caught using them and this way you cannot see the horns unless you get under the truck and look up.