I don't want to disagree with Suzy because I don't have the real HKS ssqv and she has a good point..
But on my Monza SSQV (same thing as hks ssqv) just has one adjustment screw for "hard" or "soft" spring preload and from what I understand and read on the instructions it should be adjusted to where there is no compressor surge at low boost levels, So the softer setting will vent pressure sooner than the hard setting..
The design of these SSQV is cool in the way that boost actually helps keep it from leaking unlike other types. So the soft setting should still hold boost fine.