Its real easy to understand. First, the spring always determines the lowest boost you can set because by tuning the controller completely off the only thing left is the spring. The highest boost is determined by how much you restrict the boost pressure from pushing against the spring diaphram. The boost pressure comes from the high pressure side of the turbo and is directed to the under side of the spring diaphram. With no restrictions, (Boost controller), the WG will open at whatever the spring rate is. As you reduce the boost pressure to the diaphram, (Boost controller), the total boost at the engine goes up proportionally because there is less pressure trying to lift the diaphram/spring up. I hope that helps. If you ever take a WG apart, it will be so obvious to you.
Last edited by 911rudy; 11-24-2006 at 07:22 PM..