The other point to note about them is that because they suck air in and push it through a compressor they're vulnerable to the elements... putting dirt, bugs, water etc through a compressor is never a good idea (mmm compressed bug juice!) so they include a push-on fitting for the air intake that lets you put a rubber tube on and route it to someplace less umm "elemental". Under the tank's an idea. I've yet to do this on mine but it'll make the horn last a lot longer.
