The dealership will not change your cat, regardless of what you say. They will reflash the CPU to lower the expectations of the cat, per Ford's instructions on the TSB. If you read some of the other threads, you will find that it is suspected this fix exists only to make the cat last longer than the 8/80 warranty, at which point you will have to pay to have the cat fixed. My suggestion to you is to make certain with the dealership that the catalytic converter works perfectly fine, and that if you get the code again after 8/80, then you will be having them replace the cat without charge.
I went through this about a month ago.
