What are the symptoms of a muffler needed a repack? I have just over 2500 miles on my fmf pipe. Now when accelerating I have been noticing an annoying raspy sound. Sounds almost like aluminum foil flapping in the wind.

 

Seen any fiberglass blowing out yet? You might have some separation between the silencer core pipe (usually a perf-ed tube) and the baffle wrap (either a softer-fiberglass or some sort of weird thready-looking "hard" wrap.) OR, the silencer core may be coming loose on one end, giving you the new sexy voice....
I don't own an FMF pipe. Are there rivets or screws holding the end cap on?

 

Allen head screws to pull it apart.