I drilled out the rivets on a 50cc Chibi mini dirt bike silencer when I was a kid and used steel wool to repack silencer. Back then people would take a small piece of steel wool and stick it in the end of the silencer exit hole drill little tiny dole on each side and run a piece of wire through the drilled holes and steel wool to hold in place. It helped with sound level. Back then people also used angle hair to repack a silencer. It burns, melts and gets clogged with oil pretty fast. You can tell when the angle hair gets clogged, the sound level increases. I use stainless steel or copper wool if I don’t have a regular silencer repacking material to use.