Unless there is something new out there that I am not aware of, you will probably be dis-appointed with the tankless kit. With all the kits I've seen, you will get a very short blast and that's it. What's nice about a compressor is that you will also have air pressure for tires, etc as well as all the air horn blasts you would need. I've seen some nice aftermarket compressor kits. JC Whitney has some nice kits too altho they are a little pricey. I actually have (or had) an up-close picture of the original GMC type air horn, but it is buried deep in the ATHS achives. I'll try to dig it out sometime, if you don't find a picture in the meantime.
Bill
