I did an experiment a month ago with my turbo FZ-07...
Yoshi exhaust can was the benchmark for nice stubble loudness in my opinion...size was like 53mm outlet by 280mm length I believe but it was a hex shaped can...
Had 3 aftermarket round exhaust cans of various sizes...
#1: 51mm outlet x 180mm length was way louder than Yoshi
#2: 51mm outlet x 270mm length was quieter than #1 but not #3
#3: 61mm by 180mm length was slightly louder than Yoshi but way better sound...
#3 was the winner... I also understand different motors, its potential power adder and exhaust can shape/construction changes exhaust sounds...