Chain adjustment/alignment

[LoneRanger]

When you remove an exhaust can there is a wire type mesh fabric around the pipe. Should that be replaced ? What is the purpose of it ?

Is it around the whole pipe, or just under joint between pipe and can? I'm wondering if you mean an exhaust wrap, which some use to hide less than perfect pipes. Alternatively, it is something used to seal a slight gap between pipe and (oversized?) can?