>The downside is that the FDMBC is also a one way valve, so that any pressure >built up at the wastegate actuator will not immediately go away That's why ball & spring controllers have a bleed port to get rid of that extra pressure. (There is tons and tons of info on the web about boost controllers. http://www.google.com/search?hl=en&ie=UTF8&oe=UTF8&q=boost+controller ) -Jay