Catalytic converters are devices on the underside of vehicles that clean the excess fuel, which is not burnt during the operation of the vehicle, by filtering it so that the harmful particles are converted into safe particles and released through the exhaust system. It is illegal to operate a modern motor vehicle without a catalytic converter, so it is generally not a good idea to remove a catalytic converter unless it is being replaced immediately with another. To properly prepare a catalytic converter's removal, it is necessary that the proper equipment and information be available for a specific vehicle because each vehicle places the catalytic converter in a slightly different position and configuration.
Locate the catalytic converter. The catalytic converter is attached to the bottom of the vehicle, usually in the middle of underside of the entire vehicle. Lift the vehicle using a manual car jack, ramps or a hydraulic lift like those used in a garage. Once lifted, be sure that the vehicle is securely in place so that it does not fall onto the person beneath the vehicle. The vehicle should be lifted off of the ground far enough for the person to fit under and access the catalytic converter comfortably. The catalytic converter is located between the engine and the exhaust muffler of the vehicle. Many vehicles have the catalytic converter located in slightly different places beneath the car with different pipe configurations, so be prepared for anything that you may find. The catalytic converter is the main interest of this guide but different lengths of pipes might be attached to it in front of or behind the converter; these pipes may need to be removed before removing the converter. Some vehicles have more than one catalytic converter connected in sequence with other pipes, so be sure of which catalytic converter is to be removed.
Locate and remove the O2 sensor. The O2 sensor is a device that is attached to one or both ends of the catalytic converter. Usually only the one in front of the catalytic converter needs to be removed to remove the catalytic converter. An O2 wrench is required to remove the O2 sensor, so you will need to either rent one from a garage or buy one for about £19 ($30) at any automotive parts store. Remove the pipe between the catalytic converter and the O2 sensor, if needed.
Locate and remove the bolts and/or clamps. Find the bolts and clamps that are directly connected to the catalytic converter. Spray the bolts and clamps with an automotive lubricant to loosen them. Sometimes catalytic converters are welded to the vehicle's undercarriage or the bolts are welded together, in which case they do not need to be lubricated. If the catalytic converter is welded, the bolts need to be cut apart with a reciprocating or other type of saw. If the catalytic converter is not welded, remove the catalytic converter by removing the nuts and bolts with a wrench.
Remove the catalytic converter. Generally, once the bolts and/or clamps have been cut or removed, the catalytic converter should be able to be removed by just pulling it out of the pipe behind it. Sometimes the catalytic converter connections become rusted or corroded, making its removal a little more difficult. If this is the case, tap on the end of the catalytic converter with a hammer to loosen it free from the pipe behind it.
Removing a catalytic converter and replacing it with a straight pipe will increase the vehicle's speed and fuel efficiency but not by much.
It is illegal to run a modern motor vehicle without a catalytic converter (larger trucks use other types of exhaust converters), so use caution when removing it.