Adam, The European cars with no emissions control naturally get more HP but don't burn as clean for as long I feel. Since the 70's emissions control and polluting has been a major concern in the U.S. If you removed all the Lambda system, Frequency Valve, Cat's, 02, ECU, You could adjust the engine to run smooth and run efficient until the weather changed, or altitude or a 100 other things which would cause you to re adjust the mixture. If you just unplug the 02 sensor, you will see what will happen to the mixture, you will normally run rich. Cat's may begin to glow. I know the more sensors and electronics are add to the car it's just more things to go out. But for a street car, the emissions control system when working properly will maintain the right balance of fuel and air. When I bought my 1st Delorean about 5 years ago, I changed the 02 and readjusted the air flow to match the new 02 and it's all aged at the same time. Engine runs smooth at idle, cranks fine and has plenty of pep., After a few mod's. If your car isn't idling smooth, something else could be wrong, plugs, wire, injectors, so on. Personally, I like the Lambda system to automatically adjust the mixture. I don't have to check it the way we used to. I have all kinds of books and charts on Lambda or computer control emissions. John hervey http://www.specialtauto.com/ << I am wondering what the effects of no lambda sensor are? If the sensor broke or if it was removed, would the engine idle more normally? Personally I don't like the whole lambda circuit, it makes the car idle crazy. If I just remove the sensor will it negate oxygen regulation/up and down idle? How seriously will emissions be affected, I would leave the catalytic in place. >>