Standard cat is 'rounder' than that on the ends, the rear exhaust looks like a Powerblow special.

As I posted previously, U codes are communication faults between modules, you could have a can-bus wiring fault, or a fault in one of the modules itself. Need to check resistance at the OBD connector for the can hi and lo terminals, should be 60 ohms on each. (from memory)

I did have a can fault on a mk2 Focus once and it was a poor connection on a multi plug behind the glovebox in the footwell area, was behind the carpet IIRC ended up hard wiring the can lines.