The muffler on my 450 is sounding a little wore out. I can tap it and hear something jingle. I'm betting the packing is gone. How big of a deal is it to change out the packing on these things? I've seen people act like it's no big deal but, I was unsuccessful previously.

Any tips? It's a Graydon Proline exhaust. From what I can tell basically a CT with a turn down.

 

the core in my friends yfz 450 snapped in half over rought terrain because there was no packing surrounding it. he had a drd exhaust.

 

Check this: YouTube - ATV/Motorcycle Silencer Repacking Instructions - muffler packing Step by step repacking instructions. I believe FMF sells repacking kits.