The resonator is welded into the center of the mid pipe. Where exactly is it broken?

I would say if theh stock stuff is falling apart and you were already looking to upgrade, now would be a good time to go for it. If you don't have a huge budget you can get a non-stainless ceramic-coated header (bout $275 for a DC) , some kind of hi-flow cat (universal is under 100, pre-fabbed direct fit is like $200-250), and a non-stainless cat back exhaust with some kind of coating (A'PEXi WS is like $400).

Obviously you can spend more money to get perhaps more performance and stainless pipes, but I have no idea what your budget is so that's about the minimum you would have to spend for nice, new parts.