1996 850 non turbo 2.5 B5254S catalytic converter

[bmncw]

Hello MVS
catalytic converter on my 96 850 2.5 non turbo, just removed yesterday and replace with a straight pipe, because of annoying noise and vibration. Odometer 102,000 KM.

Now the exhaust gas smells very bad. Before the catalytic converter removed, the exhaust gas was fine. Is it normal to have bad smell exhaust gas without catalytic converter or the o2 sensor need to be replaced?

No error code thrown. This car only have 1 o2 sensor, before catalytic converter.

Any suggestion for a universal catalytic converter ?

Thank you