Ok first noticed this after pulling up at a set of lights. Been driving for around 150k with no noticeable problem. As I went to take it it sounded like the snorkel was making a real sucking of air sound as I went up through the revs and gears. Sounded like the snorkel but driving it hard to pin point, just as likely to be from under the car or engine bay. Once at a cruising speed it seemed to disappear. If I knocked it into neutral and revved it no “sucking” sound, just under load but cruise control 110km and no problem and no noise. But acceleration up a hill or overtake and it’s back. Climbing the Cardwell Range it usually accelerates up in 6th gear easily but not so today. Was flat out getting over 110. The car is blowing no smoke. Any ideas?