If you have the 1.8t engine, the CAT is bolted directly to the output side of the turbocharger with a three bolt flange. It's not like some cars where the CAT is under the car and you can simply cut it out and clamp in a straight pipe. One way to replace the CAT with a pipe would be to get a "cat-delete" or "test" pipe designed to fit that specific car. Those run about $100~$175 and require some additional trickery to keep the engine computer from seeing what you've done and lighting up the CEL. If the car is to be owned in a place that does a visual inspection as part of emissions testing, the "test" pipe may keep you from passing.
Volkswagen Passat B5 FWD 1.8T > Exhaust > Test Pipe > ES#1844140 B5 1.8T Race/Cat Delete Pipe Kit - ATP-VVW-138
Is the $300 part he quoted a new replacement CAT?
OEM / Performance Parts for Audi, BMW, Mercedes Benz, Mini, Porsche & Volkswagen - ECS Tuning
Volkswagen Passat B5 FWD 1.8T > Exhaust > Test Pipe > ES#1844140 B5 1.8T Race/Cat Delete Pipe Kit - ATP-VVW-138
Is the $300 part he quoted a new replacement CAT?
OEM / Performance Parts for Audi, BMW, Mercedes Benz, Mini, Porsche & Volkswagen - ECS Tuning