The cager starts paying attention and starts looking for the ambulance, fire engine or motorcycle so then it becomes the visual thing that he insisted was the key to safety. So if a motorist does hear a siren or loud pipes he will look to identify where it is coming from. That right there wins the loud pipe issue as positive..game over done, finito!
AFAIK, emergency services vehicles sirens are designed to be directional - the white noise is particularly directional. That's not the case with bike exhausts, which is why it's difficult to orientate to find one.
It's worth pointing out that whilst the driver is looking for the source of the noisy exhaust, he's not looking at the road ahead.
FWIW, I was a motorcycle courier in London, UK for 16 years, never used loud exhausts (they are a 'copper' magnet) and never got sideswiped.
Never used the horn either , right ?
Never yelled ?
No form of noise to gain attention , right ?
YouTube - Almost crashed my Yamaha FZ6R
That was the case all the time before the exhaust mod. Now it NEVER happens. Loud pipes have probably saved my butt several times. I really could care less what everyone thinks. I want to live so the pipe stays.
Since the exhaust is not pointing that direction, it will not help at all.
If you didn't see them looking at you, always assume they are totally unaware you exist. When I say looking at you, I mean direct eye contact or looking in their mirrors.