Boost Control Solenoid - 4 Port (4BCS)Thinking of turning up the boost to max? Then this 4 port boost control solenoid is perfect. It allows for precise boost control of up to 120PSI. 4 port Boost control soldenoids are commonly used for big boost applications, boost levels can be raised as high as 6 7 times the spring pressure of the wastegate and they allow you to use lower wastegate spring pressures for more precise boost control when launching. Particularly useful in high power