Have you changed anything on the intake system recently? Does it happen within a certain rev range on the overrun?

 

That started happening a few weeks after the install with no change in the system. It happens only at the bottom of the rev range when accelerating after letting the engine doing the braking.

 

15000km in six weeks is impressive, where's the trip report?

Does it sound anything like a slipping fanbelt? Because cracks/leaks in manifolds can sound like slipping belts, and go away when the cracked bit expands due to heat. Could be a leak in the intake somewhere?

 

Not hard to do in this big country... We drove from Sydney to Alice Spring, the Tanami to Halls creek, Purnululu, the Gibb River road, Dampier peninsula, down the Pilbara another couple national parks on the way to Perth and back home.
I replaced the belt and tensioner before the trip. I checked the hoses, cannot see a fault.

 

I have the same setup as you. I have the whine when slowing down at 100kph. You have an auto can you drop it in to neutral from 100kph and see if its still there. It could be just the tyres noise as your setup has a fair bit of induction noise and when we coast the induction noise stops and you can hear the road noise. After 15000 your tyres might be getting louder. I could be 100% wroung tho

Sent from my SM-G900I using Tapatalk

 

Found the 180 degree elbow into the IC has a big hole... I did not expect the noise to occur the way it did. It actually rubbed on the plate in front of the ABS.