keep the wastegate close until the DESIRED boost pressure is reach before opening? since without such device, the wastegate will open even before the desired boost is reached but i don't know which one is really meant for it. some say boost controller just raise and lowers boost while other says it can keep the wastegate close til the desired boost is reach aside from raising and lowering boost. but some people say that it's the pressure relief valve that's why greddy have ebc, mbe and pressure relief valve and i'm confused. so which one?

 

anyone?