On both my big rig and my bus I am using the 4 chime Buell train horn kit for trucks. Go to buell.com and notice how much bigger in diameter the horn throat is by the base reed end of the horn. These horns really get out and have a distinct tone to them (purposely toned differently then any available train horn so not to be mistaken for a train). Good Luck, TomC
Tom, it's http://www.buellairhorns.com
The other site gives you motorcycles, which is kinda related. Perhaps we can do a "Mythbusters" type of experiment to see if we can blast a Buell motorcycle off the road with a Buell airhorn?