The throttle body is an important part of your air intake system that controls the air flowing into your engine. It's located between your air intake and engine manifold where fresh air is pulled into the engine for the combustion process. Like all other components in your 2008 [MALE] F-150, factory throttle bodies are OK for an unmodified engine. Once you have an upgraded performance vehicle, and a performance tune, you will be in need of a new throttle body. Since the engine is basically a large air pump, increasing the air intake level with a new throttle body will increase the engine's power output as well, in some cases by up to 15 to 25 hp.
While increasing horsepower is the main reason someone would add a larger throttle body, another benefit is added throttle response. Many auto manufacturers measure a car’s airflow at the peak RPMs and then choose a throttle body that ensures 50% of throttle will produce 50% airflow. While that formula works for everyday driving, it’s not optimal for those with high performance vehicles. By adding a larger throttle body, you’ll feel a sharper increase in the engine’s responsiveness, especially at a higher RPM, since the engine’s airflow is increased.