About 40, it boost it to 200 HP. The supercharger kit from scion come with bigger fule injectors as well as a rage CPU to produce more power. It also has a warranty Wich most superchargers do not have because they easily break.
Remove the radiator cap when the engine is cool and add the coolant into the radiator or you can add to the coolant overflow bottle. DON'T remove the radiator cap when the engine is hot!!!
It depends on the motor and the amount of boost. Normal atmospheric pressure is 14.7 psi, so that's the condition your car is running in while naturally aspirated. If you add a turbo that provides...