A transmissions role in your car is to act as a regulator for the amount of power going to the wheels at any given time. It makes sure that the power is exactly where you want it to be and never too much or too little. Through proper gearing, you can make sure your transmission can hold your power goals at any given time. Through addition of an LSD, you can ensure traction remains fluid on both sides of the car. Building a proper transmission is just as integral to building a high functioning car as all other components, so make sure to always keep it in mind with relation to your end goals!