2004 Passat GLX V6 post-converter and coolant leak repairs

This is the engine running after replacing the catalytic converters/downpipes and fixing a coolant leak. The engine is running so much quieter, now ;)

The coolant leak was vexing to sort out, but the end fix was to replace the o-rings in the fittings of the heat exchanger hoses. RKX sells them as a set in the correct size (RKX-KIT-004). One of my old/original o-rings had clear signs of wear and was the source of the coolant leak.