Rattle inside Muffler
 

I have a 2001 Boxster S that I just had the IMS bearing replaced with the LN kit(81,000 miles showed hardly any wear on the bearing according to the shop). Now I hear something inside the muffler rattling. Not like something dropped into it but possibly something coming loose inside(baffles)? Any ideas what to do other that replacing the muffler? Any issue with not replacing anytime soon other than dealing with the noise?

As long as it's in the muffler it can't hurt anything. If you took the muffler off you may be able to get it to fall out the inlet pipes or find someone that can cut the muffler open & take it out while modifying the pipes & insulation for louder sound if you want.

i noticed most boxsters have the same problem - mine 2 -. had it inspected blamed on cat. converter "may be" going bad being a $1000 replacment i thought i can live with.

btw, the mechanic removed lots of stones and other stuff held between the muffler and insulation, it helped a bit.

The element inside the cats have been known to detach from the shell and rattle around. This might trigger a check engine fault and you'll need to replace it. Might be a good time to find a used one from someone that has put on aftermarket exhaust or go the aftermarket route yourself.