I recall a remap may be required on ECU to negate post CAT O2 sensor presence and so avoid fault code. This because before and after sensors are used collectively to monitor CAT performance. Might it already been done in your last remap though
Richard
2018 Roadster 3.7 1966 Land Rover S2a 88 2024 Royal Enfield Guerrilla 450 1945 Guzzi Airone