I went through the ecu box as its completely sealed then hid all of the wiring behind the dash. Bit of a pain to do, removing wipers and scuttle panel but it hides everything away and keeps it water tight, there is a guide on a4mods on how to fit the boost gauge and where to tap the boost hose into. If your gonna fit it when it's cold get a cup with hot water in to make the boost hose supple, make it a lot easier to fit on the t piece and get a nice tight fit