Is this a myth? I know over time glasspacks sound different but do chambered mufflers?

the reason I ask is because I went to the muffler shop today and had my tips moved to in front of the tire. lightning style lol but its sounds kinda drowny. at idle its fine i really like it but the upper rpms its not so good.

hopefully it changes if not ill just move it again

 

Chambered mufflers do not break-in, but they change tone very minorly overtime due to burning of plates, settling of soot.

 

hmm i think the reason it sounds bad is because i have two 3" tips i plugged one and it sounded a little better. oh why did i change a good thing