Loud Pipes Save Lives
Yeah, there are a few situations where full-time noisemakers might help a driver notice you, like when you are right next to someone who is about to change lanes. However, all that noise directed rearward doesn't do much in the most common and much more dangerous conflict in which a car turns in front of you. Maybe it's the fatigue caused by the noise, maybe it's the attitudes of riders who insist on making annoying noise, or perhaps loud bikes annoy enough drivers to make them aggressive. Whatever the reason, research shows that bikes with modified exhaust systems crash more frequently than those with stock pipes. If you really want to save lives, turn to a loud jacket or a bright helmet color, which have been proven to do the job.