Excuse me if this has been covered before, my Audi (1.9 tdi, 130 sport) is my casual run around, I service it but don't know the ins and outs of it. I've got a Defender that I have been playing with and thought I'd do a couple of bits to the A4. I'm thinking of fitting a grainger valve to up the boost slightly, obviously would fit a boost gauge to keep an eye on any spiking or creep. I have had a look today and the vacuum pipe that connects to the turbo actuator doesn't connect to the inlet manifold, it goes to an electric valve? What on earth is this??? I'm used to the actuator opening, as it feels the pressure at the manifold. Couple of questions. What is this valve, and what seems like an accumulator next to it also taking a feed from it? Can I pop a grainger valve in between the valve and the actuator? Would this work? As in delaying the opening of the waist gate. That saying that the actuator works on pressure, or is it vacuum? Or could I just tap a take off into the manifold and run a pipe to the actuator? Then plug where it came from this valve thing? Any help would be great.