Prairie...you are 100% correct, there are lots of people who we check, who as they pull away we say...those are stingers.....but drive away civilized...and we ignore....then there are the ones who wail towards us or away as agressively as they can, making as much noise as they can, maybe obeying the speed limit...they get tagged. Also the ones we hear coming for 10 minutes....one guy last week we listened to for 10-15 minutes terrorizing the town...I went and found him...he was twice prohibited from driving, had no insurance, etc, and will likely do a small amount of time....I told him if it wasn't for his pipes...we wouldn't be dealing with him.
There is no question atleast where I am, if you drive sensibly, your pipes will go unnoticed...can't speak for Quebec though.
Another point....most people who are not very familiar with our 4 strokes, wouldn't be able to tell if the pipe was changed, since the changes are under the seat...even taking a picture wouldn't be much proof...if a guy was to switch back to stock later.