Turbosmart's EFR-specific dual-port actuator allows for much greater levels of boost control precision. While normal single-port actuators can only use boost pressure to open the wastegate, this dual-port actuator (when combined with a 4-port EBC valve) can both open and close the wastegate actively. This results in improved spool-up, less target overshoot, and better high-RPM power.
The 4-port valve is able to direct air into two distinct chambers, one ahead of the actuator diaphragm and the other behind it. This allows the ECU to actively open or shut the wastegate as it needs to in order to achieve desired boost levels at all RPM.
The Turbosmart EFR actuator ships standard with the 7lb Middle and 7lb Outer springs for a total of 14psi of spring pressure (sorry, no substitutes). You may order additional springs to run as low as 3psi or as high as 26psi. You cannot run less boost than spring pressure regardless of EBC settings (i.e. installing an 11psi Middle spring means you will only be able to run 11psi or higher).
Slight trimming of the hood bracing is required to clear NA and NB hoods.
Inner, Middle, and Outer springs may be combined to achieve a variety of wastegate boost levels. For example, to run a 17psi base pressure, use the 7psi Middle and 10psi Outer springs together.