Can you not use a straight pressure test and just listen for the air escaping ? - As a matter of interest I had a leak in the seal around the IAT sensor and one of the vacuum lines under the inlet manifold (going way back)

. Next to mount my catch can....
Also for those of you who know a bit... when removed the n249 plumbing I noticed there was a one way valve that sat inlet manifold side of the valves. Should I refits this? Guessing it’s there to prevent airflow going the wrong way in the vac lines
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