Decibel numbers are useless without precisely describing the circumstances surrounding that number. If they are using the SAE J2825 test (Oakville, Caledon bylaws are based on that) then the measurement has to be 0.5 m from exhaust outlet, behind the vehicle at a 45 degree outboard angle of the exhaust outlet and at the same height - this precisely defines the point in space where the measurements have to be taken - and there can't be more than a certain amount of background noise and there can't be hard sound-reflective surfaces within a certain distance other than the road surface itself.
The 92 dBA at idle is an easy test, but the higher-RPM test (5000 rpm steady in neutral for engines with 3 or more cylinders, 2000 rpm steady in neutral for engines with 2 or fewer cylinders) is subject to vagaries ... prove that RPM number. Bike has a tach? It's not a certified instrument. Are they doing it with a vibration/frequency analyser? That's not a certified instrument, either. Most bikes don't have easy access to the end of the crankshaft for a suitable instrument to be used. Getting to the spark plugs on my ZX10R is a 3 hour job that requires tools and the workshop manual, and doing it requires throttle body removal ... can't do that with the engine running. It is literally not possible to use an ignition pick-up tachometer without dismantling the bike to get to the spark plugs, putting the bike back together with a wire running to somewhere from whatever instrument you have, then dismantling the bike again to get the instrument back out, and putting the bike all back together again ...
As far as I can tell, Caledon OPP stopped applying the higher-rpm test, because it was futile to do it in a way that will stand up in court. I haven't seen them enforce their noise bylaw at all for quite a while. But ... perhaps objectives were achieved, because there are noticeably fewer straight-pipe cruisers passing through nowadays. (edit: Seems that they've switched to loud stereos, instead)
