Alot of people forget or don't understand the principles on boosting cars. High psi figures don't really mean much. What you want to achieve is a high CFM amount going into the intake, which is where the lower pulley comes in. The supporting mods are so the engine can allow it to handle the amount of air coming in, and the flow allows it to be able to escape without building up pressure and launching your heads off the car like a NASA space rocket.