My Toyota has a twin box exhaust system, standard diameter, with cat.

i was recently pulled over by VOSA for a random stop check. When that was measured the reading was 102db! obviously, the car failed (the max acceptable road limit was 90)

what shocked me was i didn't consider the car to be offensively noisey at all!

to get the car to pass i had to weld in silencers over twice the size of the original ones