Under part throttle when the turbo is spooling it sounds like I hear it fluttering some but I do not feel it in the acceleration. I am not sure if this is a characteristic of the turbo or not. Or just me being paroniod. It is hard to tell because I can barely hear the turbo at all. Anyone else experience this?

I haven't noticed this behavior at all.

Most likely the BPV keeping boost from building under partial throttle.

Most likely the BPV keeping boost from building under partial throttle.

What he said.. :) have you got an after market air filter on by chance?

easy solution...dont do part thottle. :)

could also be wastegate flutter.

i know a lot of Subaru owners always post up about flutter when they install an aftermarket downpipe (or downpipe + O2 housing in the Evo world)