What is this N75 valve and how does it effect my car? From what i have read it comes with my car. What does tampering with it or buying the ecs tuning one do? Any help would be greatly appreciated.

 

The N75 is the valve that regulates the wastegate positions.

When its unenergized it permits full charge pressure on actuator diaphragm. So the turbochargers naturally regulate themselves in a sense.
As boost builds, the wastegate opens.

The ECU can operate the N75 to vent some of this pressure so the wastegate either does not open, or opens less.

Simply put, it uses the various sensors on the engine to adjust the wastegates to control turbine speeds and in turn controlling boost pressure at any given rpm.

The ECS Race valve just modifies its control a little to carry a couple more lbs. of boost throughout the low-mid rpms.