The car only has one EBCS (Electronic Boost Control Solenoid). It's mounted to the turbo and controls the wastegate. Its operation is variable, as in the ECU can control how far the valve opens.
The other valve on top of the valve cover is the BVS (Bypass Valve Solenoid) and controls the turbo's internal Bypass Valve. It's binary and can only be either open or closed.
IMO, the valves are of good performance and quality. The OEM EBCS is a 3-port design, some have "upgraded" to a 4-port valve on some of the bigger turbos for a bit more granular boost control. A 4-port valve is able to hold the wastegate closed with greater force than spring pressure. I see no need to upgrade the BVS.
