Hi, My opinion would be that that this does not affect the lambda system. If you decide to remove the Oxygen sensor then adjust the mixture screw (allen key) in the fuel distributor to give a CO content of 1-1.3% by volume. Always ensure the rest of the engine and components are fully working OK prior to adjusting fuel mixture. I am not sure what the MOT requirements are in Norway but in the UK for pre 1986 cars the max allowable limit for a pass is 4.5% CO and 1200ppm HC with no visible smoke when idling. A cat isn't required for this year of car but please check with your countries emission laws! Hope this helps. Nick. Stian Birkeland <delorean@xxxx> wrote: Hi, If you swap the cat with a crossover pipe, would this effect the Lambda-system? Would the Lambda sensor not be necessary any more? Would this also effect the actual CO2 emissions testing / passing on the MoT? Best wishes Stian Birkeland Norway VIN # 06759 --------------------------------- Yahoo! Messenger - Communicate instantly..."Ping" your friends today! Download Messenger Now [Non-text portions of this message have been removed]