Sorry to hi-jack the thread... I have also a questions of the engine sound that am not certain of. It gives rather loud 'sucking' noice as I open the throttle from idle.
Then on same time I noticed rather odd lookin movement on the intake as I press loud pedal a bit - the intake runners move slightly away from each other and plenums raise up a bit same time.
Is these two above normal in your opinion? Car does not throw CEL and drives otherwise real well.
Then - another noice the patient shows, is a 'chirp' as I press the gas a bit from the idle. This chirp does not show except when I take off from standstill.
All above can be seen/heard on the video at this link:
https://www.dropbox.com/s/xvbi7kjatak6611/Boxster%20986%202_7%20engine%20move%20and%20sound. MOV?dl=0