Hello Adrian,
I cannot specifically comment about the Vitara, but in general you don't get something extra for nothing.
Some car manufactures do offer remapping the engine management to improve towing (Honda did for their legend model).
Most modern cars use a microprocessor to manage the engine in response to speed and throttle, and the manufacture will have programmed it to produce a set combination of power delivery.
Most chipping companies do one of two things or a combination of reprogramming the computer (know as remapping) or corrupting the signals from some of the sensors. This make the engine perform differently, and different torque and power outputs can be produced.
Quite simply if you increase either power or torque at a given engine speed, you will use more fuel, and therefore more particulates and emissions, However that is not always the whole story. The engine may be remapped to produce more torque at lower revs which aides acceleration, but it may be made to run leaner at higher rpm, which might produce better mpg at higher speeds.
There are always some risks from these sorts of modifications. Firstly, if you are putting more power through the transmission, it may be in greater danger of breaking. The engines running temperature may altered which can produce problems with deposition carbon, the valves may not be able to cope with extra heat, and the lubricating oils may not provide the necessary protection etc.
The modification may render the car an MOT failure of emissions.
It may invalidate the manufactures guarantees, and of course you must tell your insurer that you have modified the car.