I have 2 Bad boys on my bike, both facing forward. While they are very loud and will make most people jump, they still do not have what it takes at freeway speeds. That wind will knock the dBs down real quick. There was a time I was trying to get the attention of another bike. While at highway speeds, he could not hear my dual Bad Boys until I was about 10 feet behind him.
Most horns on the market are rated for dB at 4 inches. Sound looses half of its sound level if you double the distance. So every time you double the distance you lose about 6dB
So a horn advertised with dB rating that does not give the distance it was measured at, is a totally meaningless number. By the time a cage is 4 inches from my horn, it is to late for me.
My goal is to get train horns on my bike, they are rated 120 dBa at 100 feet. A Bad Boy or Steible will be about 68 dBa at 100 feet. That is equal to the sound in an office setting. Or the high end of normal conversation.