My muffler is noisy can that be the catalytic converter?

yes, the cat converter assembly is about 1200-1500 installed. Roy

Well if it just a heat shield i would just take it to a muffler shop and let them fabricate a shield on it. I would not pay for a new cat converter. I never heard a converter rusted out since they made out of stainless steel. If it is broken that is a different thing; then needs to be replaced since conveters can't be welded.