Go to
www.hornblasters.com they have a bunch of different kits. I have installed 2 of them on my own vehicles, including my H2. They are around 150db.
Just be careful when using them. I usually won't use them while driving next to vehicles, because you can really freak someone out and cause an accident. Although I do use it if some jackoff does something stupid though. It's fun though scaring some people walking down the sidewalk or 30 people sitting at a bus stop.
