There has been a lot of talk about air flow through the cabin recently, here are my two cabin vent(s) on either side of the main tube. These are 42mm, cut to fit a vent from Car Builders Solutions (sitting on the tube). There were previously 2 brake line holes in these spots, one of them quite large ~30mm, so rather than fill these in, I enlarged them.
The vents will be fitted to ~150mm flexi hose tucked in front of the rear torsion tube, visible through the holes.