My muffler is noisy can that be the catalytic converter? on 2003 Lexus RX300

The garage says that the sheild above the catalytic converter can collect water and has rusted and I need a new catalytic converter. The only sympton I believe is the muffler noise. The noise started several years ago and went away but is back now. Is this an expensive repair?

Asked by for the 2003 Lexus RX300
yes, the cat converter assembly is about 1200-1500 installed.

If the only problem is a slightly noisey muffler can I just continue to drive it. There is no loss of power.
2 more answers
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.
I looked up the parts for youre car and there are three catalytic converters a front, center and rear,all three total up to about $2400.00 plus labor,