The top holes will be plumbed into the cockpit to regulators so I can adjust boost from there. Pressure will first come off the intake manifold to the regulator and then to the wastegates. If I just add a filter to the top of the wastegates, they will always open at the factory rated pressure. If unregulated manifold pressure is plumbed into the top of the wastegate, that pressure will assist the spring and the valve will never open.