More likely the pinging is caused by carbon buildup, in which case BG
44K is not a bad idea but you probably would need something stronger,
like GM Top Engine Cleaner.

good luck

nate

   Your answer is Yes, a muffler stopped up from being broken apart inside,
if its pieces cause an undue restriction to exhaust flow, can exert a load
on the engine & cause pinging.  Also a stopped up cat. convertor or a
collapsed inner wall of a 2-wall exhaust or tail pipe can do the same.
Usually when the cat. convertor becomes clogged from contaminated
'honeycomb' or 'pellets', or the pipe is stopped up from collapsing, you
hear a 'whooshing' noise when you attempt to accelerate.  You DO know what a
whooshing noise is, don't you?  (Hopefully it's not just a colloquial- ism.)
HTH, s.