Finally got around to designing a vent pod for the Mk4 Ibiza air vent (which I believe is same as Mk3). This allows for a neat and OEM style fitment for a boost (or other) gauge. I use 45mm gauges in my cars as they fit the vent housing a little easier. I have also designed a pod for 52mm gauges. The pod replaces the stock air vent internals which clip out and the pod is fixed in place by clips in the stock vent surround. Let me know what you think 
Stock vent surround used in conjunction with vent pod:
45mm Gauge and Pod:
52mm Gauge and pod
Stock housing and pod. This picture shows how the open/close mechanism of the stock vent housing would block the gauge. Thus the stock housing is not used.
I made a version of the housing with no internals, basically just a tube which connects the vent surround to the vent pipe in the dash.
Stock vent surround used in conjunction with vent pod:
45mm Gauge and Pod:
52mm Gauge and pod
Stock housing and pod. This picture shows how the open/close mechanism of the stock vent housing would block the gauge. Thus the stock housing is not used.
I made a version of the housing with no internals, basically just a tube which connects the vent surround to the vent pipe in the dash.
