I've got a similar setup on my SUV from hell. My setup is real train horns and a bigger compressor tank. They are funny in videos but I don't use mine around people unless I warn them or don't like them. My family was in town and knew it was coming (ears plugged) and it still made them freaking jump. My mother said she could feel the ground shake.
Like I said... a great novelty but not something I use in traffic (unless I'm REALLY pissed off). Supposedly, it's a $1900 setup on my truck (it came already installed) and I can't imagine spending that for a novelty. The real benefit for me is an air jack on the back bumper that I can hook a hose into to fill tires or run air tools! :cool: