Review on Dorman 674-830 Rear Catalytic Converter with Integrated Exhaust Manifold for Ford/Mazda/Mercury (Non-CARB Compliant) - Compatible Models & Reliable Performance by Nick Grays

Unlike the front cat, this one requires a PITA to be installed. It looks like the whole car is about to fall apart. NOx and CO are lower than last year with OE cat. The kit corresponds exactly to the old part. Looks high quality. Be sure to use new mounting nuts and bolts and lubricate them before installation. Cat comes with new downpipe bolts. I also installed new Denso oxygen sensors and coils/spark plugs. In the near future it is planned to install an aftermarket sport exhaust (Magnaflow Borla etc.), the sound with it and the OE muffler is good. Seems to be louder than before but I drove with a partially congested one for a while my memory was fuzzy.