Air box lid and filter off and MAF/turbo inlet hose off. The three Torx screws that hold the air box lid on and the two that hold the MAF sensor pipe to the air box use the same Torx bit, as do the two screws that secure the air box to the top of the cam cover. Then there is the 8mm headed bolt holding the induction pipe to the MAF pipe bracket:

The induction pipe needs to be removed at this stage. The front section (that extends forward to the grille) needs pulling off the plastic pipe that curves round behind the back of the engine, no clips. Follow that curved plastic pipe round, and then that needs pulling away from the air box, again..no clips. At this point all that holds the air box onto the engine are the rubber washers (the plastic feet on the bottom of the air box simply push down into these, so removal needs nothing more than a firm pull upwards), the wiring loom clip (with a red ring around it in the photo below - this pulls away from the plastic flange on the air box [push away from us, if looking from the same angle as the photo below]) and the wiring loom multiplug connector to the airbox (pic coming up later):

Air box now removed, and the wiring loom multiplug is identified (and magnified) to show the "barbed" rubber fitting on top. There is an oval cutout in the airbox inlet mouth into which this barbed fitting is pressed. To remove it, allowing you to completely withdraw from the engine bay, you need to pull the multiplug downwards and at an angle, to free the rubber through the hole:

The all-important commonrail connector, as viewed from the driver's side wing:

I fiddled for about 5 minutes, trying to get fingers onto the connector, then decided a far better idea would be to fetch my long-shafted (probably about 12-15cm long) flat blade screwdriver. Immediately I was able to flip up the tab on the connector and withdraw it:

A tiny strip of plastic on the underside of the Ford connector needed trimming off to allow it to click into the Van Aaken connector, then it's a case of plugging in the Van Aaken connector to the commonrail, which was mildly fiddly, but took no more than 30 secs:

The inlet piping as removed from the bay:

So I fitted it all back, secured the tuning box and went for a spin, and boy is it fun! It will now spin up in first on a less-than-perfect surface (which it didn't before) in first gear, but useful power now spans from 2,000 right up to about 3,800rpm instead of around 3,100rpm as it was before, and the power in that range is markedly higher than before. 

Info Thanks to heeman10 Turbo Diesel Owners Club