I agree with some of the article. You do not and can not hear a motorcycle approaching from the rear at a speed from 45 on up. I don't care how loud the pipes are you won't hear it with the windows up and radio on. With windows down then possibly yes when they get close enough behind. As far as wild life yes, it will hear you approaching because it's stationary and could save your life because you caused them to move before you were upon them. On the other hand the loud exhaust could spook them and cause them to act irrational to get away from the noise. I had 3 HD's with very loud and obnoxious pipes (kind of embarrassed to say) and freeway drivers never saw or heard me until I was passing them and I would see their car swerve a little because I scared them. With the loud pipes I knew when passing do it fast because when beside the car the driver would then hear the exhaust and suddenly react. It became a game with me actually. If everyone is stationary such as in town slowing for traffic lights and heavy traffic then everyone can hear your bike so they are aware of you but at highway or freeway speeds then no, they are oblivious to you behind them. Only my opinion and what happened to me. Cheers.