One, decibels are a logarithmic unit. Two, you are comparing factory exhausts on the Harley meant to comply with noise regulations with top of the line aftermarket race exhausts for the Honda (which is probably as loud as you could make the Honda without removing the pipes entirely). They are not anywhere near each other - and the data in [1] really makes that point, I'm not sure how you concluded that most motorcycles are anywhere near each other in sound output.
That's not a good statement. Just because a number is logarithmic does not make sound logarithmic...Here is a video that shows two different exhaust with similar dB output: https://www.youtube.com/watch?v=Ax6W-V9bsmg
> Two, you are comparing factory exhausts on the Harley meant to comply with noise regulations with top of the line aftermarket race exhausts for the Honda (which is probably as loud as you could make the Honda without removing the pipes entirely). They are not anywhere near each other - and the data in [1] really makes that point,
