SAI solenoid valve - it sits on top of the fuel rail in that corner. You can just see it next to the breather hose in my second pic, with two vac lines connected to it. The vac input goes to the front where the manifold valves are, the vac output goes down the back to the kombi valves.
The red arrow points at the valve. The green line is the vac supply from the front - this is tee'd in to the main vac line to the reservoirs in the wings. The yellow line is the feed to the kombi valves, tee-d underneath the round oil separator pod.
