What happens if you remove the catalysts off a jaguar s type?

Your vehicle will most likely gain a very small speed increase due to increased exhaust flow. However, it will also be illegal for sale or transportation into areas that have emissions controls (California for example). I have had the Catalytic Converter removed from every vehicle I have ever owned because I get ticked when they clog up. But I live in an area that doesn't have emissions laws, so I really am not affected by it.