Outer Limits 4x4 Board

If I lose the cat will the 3 litre breath better or is it an integral part of the engines setup.Any help would be much appreciated.

catalytic converter filters out pollutants in unleaded petrol

If you want the engine to 'breathe better' add a larger diamater exhaust system, with appropriate sized muffler and catalytic converter

And I think it's illegal to remove it from your vehicle