The waste gates are set for 7 PSI and the boost is increased thru a bleed off process. The hose connecting to the waste gate is supposed to have a metering orifice inside it (often called a pill). In normal mode the safety boost valve bleeds off pressure in the line so that the waste gate only "see" 7 PSI while 9 PSI is delivered to the manifold. When detonation is detected the safety boost valve cuts off the pressure bleed and the waste gate "sees" all pressure. Sometimes people replace the lines supporting the whole process and the new line does not have a restriction in it, which prevents the bleed process from working working.