The straight answer in most cases is no. Many petrolheads out there decide that the converters unlimited is producing a severe blockage within the exhaust system that needs to be eradicated and therefore delete the cat from the system altogether, replacing it with a straight pipe. Although this will ramp up the volume of your powertrain and potentially eke out a few more horses from your engine, in most countries, driving a car without aconverters unlimited is deemed illegal.
Cat stripping is also another form of decatting, which is the process of removing the honeycomb innards of the cat to simply reduce the amount of restriction inflicted on the exhaust gases.
Most people who go down the route of a full cat delete decide to chance it and simply have a cat waiting to put back in place for when MOT time comes around. But get caught by a keen police officer with a flashlight and it could be game over. And considering the horsepower gain could potentially be counted on one hand depending on the size of the engine, a sports cat seems like the much more viable option if you really feel like the stock cat on your car is holding your powertrain back.
The impact of decatting will be amplified in a turbocharged car however, as the removal of a precatalytic converters unlimited would allow an increase in flow of exhaust gasses into the turbocharger. converters unlimited work best when at high temperature, so a precat is a smaller version found higher up the exhaust system to help break down emissions at start-up when the engine is running very rich.
In a turbo exhaust system, the precat generally sits just upstream from the turbocharger, therefore a removal would derestrict that area of the exhaust. But yet again, that would be deemed as tampering with a standard exhaust system’s emission controls and would be considered illegal in most countries.