Anyone think this could be compressor surge? I think that turbo is sized accordingly and should not be out of its efficiency range.
http://www.youtube.com/watch?v=nCj6Spwl1CU Watch :45 - 1:00 Does it sound like that?
No, not really. It sounds more like the BOV is not closed completely, like a weak fluttering blow off? But it only happens in the higher RPM like 5500RPM and above, below that it holds closed just fine. I'll let ADC have fun with that