As promised here's the steps took to DIY fit boost gauge to my 9n3 GTI. I've only really included the major parts as some of it is so obvious it'd be a waste of time writing down.
This is not a 5min job and leave a few hours!
Good Luck!
Important Note - This is just a guide as to what I did, so follow these steps at your own risk. I'm not being held responsible if you follow this and as a result either hurt yourself, someone else or damage your car!!
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Parts used not supplied in kit -
9mm fuel line clips
Inline fuse holder + fuse (1amp)
Extra cable ties (small)
Ring crimp connector (for ground wire).
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# Removed side of dash using a flat blade screwdriver to reveal fuse board. This needed a good sharp tug to undo the clips.
# Air vent assembly is held in dash by 4 metal clips. Use hand to push the bottom edge of the vent outwards to release.
(Tip - wrap blade of screwdriver in tape to prevent it marking dash).
# Disassembled air vent.
___#1 Disconnect arm for vent on/off flap (red circle)
___#2 Remove silver vent face. This is held on by 2clips on either side (yellow circles) and a further 2 on the top.
(The clips are tight, and found once you release one side and have a go at the opposite; the clips would spring back in again... I ended up releasing the face with 2 old dinner knives in each side).
# Removed both vertical and horizontal vent slats (held in by similar clips to vent face).
# Drilled a hole in bottom of vent to allow hose and wiring to pass though.
# Attached hose to gauge with supplied fittings in kit (used 90degree threaded connector and longer rubber tube into long vacuum hose). Used teflon (plumbers) tape on the threaded connection to ensure good seal is made, cable ties to secure hose connections.
# Assembled boost gauge into pod, and then pod into vent shell... clipped vent assembly together loosely and placed loosely into dash.
(Left vent arm for on/off flap disconnected. Once installed in the shell, the threads at the back of the gauge sit tight against the vent flap holding it closed (The design of the pod as described doesn't allow airflow to the bottom section of the vent anyway). The on/off dial still feels weighted without the arm being connected anyway and connecting it would only make the dial feel like it was jammed. Note: the closed vent flap doesn't prevent airflow to the upper vent slats that are still operational).
# Feeded hose under the dash through to the passenger foot well (secured hose with cable ties once install complete).
# Feeded hose through grommet in passenger foot well (a little washing up liquid and a short length of stiff wire required to get it through).
# Other side of grommet in engine bay is located in the area under the ECU. To get at this i loosend the top off the airbox and just about managed to grab the cable.
# Feeded hose and cable tied to neatly in engine bay.
I've done quite a bit of reading/research as find the best place to T-off the line for the boost gauge. I believe there are a number of places where it can be done (eg: off top of DV valve) but the vast majority of advice I’ve come across points to the hose between the Fuel Pressure Regulator (FPR) --> Inlet manifold... So I chose to do that!
BEFORE
AFTER
# Chopped around 10mm out of hose so once T-piece installed, everything sits nice and neat.
# Used 9mm fuel line clips (wasn't supplied in kit) to secure existing hoses in T-piece.
NOW TEST THE GAUGE WORKS!!
Now the electrics....
The kit was supplied with scotchlock and crimp connectors.... which I’ve never been a fan of, so I chose to solder and heatshrink insulate all of my connections however still can be done with the kit supplied.
# Disconnect car battery
# Need to have access to wiring at back of the lighting controls. Lighing switch can be removed by pressing light switch in + turning to side-light position at the same time.... which then allows the unit to be pushed loose out of the dash.
# Cut Gauge wires down to decent length.
Live (Red) wire
# Cut wire and Splice on resistor.
# Attached an inline fuse holder (loaded with a 1amp glass fuse) to the end of the wire red wire.
# Soldered other end or inline fuse holder wire to the Gray+Bluestripe wire behind the lighting contols and insulated.
I Used this resistor (supplied in the kit)
This photo is where the 'Red LIVE wire' inline fuse holder meets the Gray+Bluestrip wire behind the headlight controls.
(Note: In this photo, the colour of the wire of the inline fuse holder happened to be black.... which looks slightly confusing)
Note/Warning:
I used a New South Performance 'Spectrum' gauge in my install, I found that the voltage running from the dash-lighting dimmer switch in the car is less than standard (even on max), and is not enough to illuminate the gauge properly (only the needle lights up and not the backlight). To solve this, I sourced power for the gauge illumination on another feed which turns on with the lights - The Gray+Bluestripe wire mentioned above.
Negative (Black) wire
# Removing the air vent reveals lots of metal work with various torx screws attaching various parts of the dash together. This metal work is a good earth.
I attached a crimp+soldered ring connector to the Black wire and fastened firmly it under one of the torx screws in contact with the metal.
.... Connections done, re-connected battery and Gauge illuminated when lights are switched on!!
Good Luck!!
