BOV type of sound coming from exhaust n54

[Kashvir]

Sup everyone,

Got a bit of a weird occurrence happening on my car. Hoping someone can shed some light or a direction on where to look.

So like the title says I'm getting a sort of blow off sound from the exhaust at about 2000rpm when my foot is off the accelerator pedal. A light rev replicates the sound. This is the only time it happens. When I'm accelerating there isn't any strange sounds. There isn't any change in the car performance, nor are there any strange engine sounds. The sound started happening after sitting in some bad traffic on one morning. Pretty stumped on where to look next.

Mods on the car are:
Charge pipe with stock DV
Downpipes
Exhaust
Inlets

Thanks in advance for any help

 

[NBN]

Test to see if your stock diverter valve is leaking, there's a diy on n54tech. What tune are running, what does your logs say