well, unless the wastegate has a line on both sides of the internal diaphram, that would be impossible! usually the spring is plenty strong enough to hold the valve shut and the positive boost pressure works against the spring to open the valve. adjustment is made by tightining or loosening the spring pressure. i have never seen an external wastegate that still uses a solonoid! please explain! you mean there are two sealed areas on each side of the diaphram? one would help valve to open with boost at a certian level(normal), and one on the back side of diaphram that could be used to help the spring stay closed. i don't think so.