Yes, that is slight surge heard as the BOV fluttering. It's not really that bad for the compressor - what is bad is compressor surge that occurs under load when the turbo outspools/outflows the flow capacity of the engine at a particular RPM. This happens a lot with stock-housing turbos on the Evo when you mess with cam timing to improve spool up.
I'm guessing 370Z's need a BOV like the Synapse since we don't have a lot (if any) vacuum available when you transition from WOT to off-throttle. This is due to the inherent throttle body behavior in the VVEL-equipped engine (butterfly valves are almost always open while the engine is running).
__________________
'10 PW 370Z 7AT - wife's car - Project Raspberry Cheesecake
'08 Evo X - built motor+trans | BB-X @ 32 psi | CH3OH | self-built+tuned - ??? WHP
'01 Galant V6 - built motor | GT35R | self-built+tuned - 550+ WHP (retired)
|