Is flex pipe needed?

Judging by what you stated it sounds like it has had a rough life. If it all beat up and hasn’t be maintained properly it might not be worth it. Figure out the book value and weight that against the cost of repairs. Some 14 year old vehicles are worth fixing while others are not.

Site error.

Catalytic converters don't just get clogged from use or for no reason. Sounds like the engine has been misfiring, overheating the catalytic converter, and just generally neglected. The converter needs to be replaced, along with the flex pipe AFTER the engine problems are addressed. Then the motor mounts and possibly transmission mount needs to be replaced. Getting back to the catalytic converter, you need to know what emission control system your vehicle has to get the correct converter. The emissions decal under the hood will tell you. You can probably save some money by buying a universal catalytic converter instead of a direct fit one. You can get an idea of what the parts will cost by looking at rockauto.com but, personally, I'd replaced the vehicle and take better care of the next one! Jim

Engine has been well maintain. No misfires

Based on what I’m seeing you have three catalytic converters. A right and left exhaust manifold and the third is down further in the exhaust system, past the flex pipe. Did that third converter get clogged from the flex pipe falling apart? The flex pipe section and catalytic converter can each be replaced separately by a good muffler shop. However, you still need to know what emission control system you have to get the correct catalytic converter(s). You can view each one and their prices on rockauto.com to give you an idea. The flex pipe section is not listed, but they're out there. Jim