EDIT: Removed some stuff that is irrelevant
First person representations of what the bov is doing backed by only onomatopoeia and the tial "general vacuum" guidline recommendations are not trustworthy enough to overturn physics. Lets please use science derived discussion.
You're making lots of definitive statements based on a 'vague and general' guideline from Tial (which isn't written for minimizing surge on delicate hybrid turbos) and your own results (which are subject to many variables and in my opinion suspect). You have not explained how your car manages to defy the physics of how a BOV operates. If you want to use Tial's recommendations, ask them to see their chart for cars with drive by wire throttle blades.
What you guys are unable to do, is explain how a 10 psi spring is better than a 9 psi spring, in terms of reducing surge. Unless you can do this then you are merely speculating. Using the old "Well I have a friend who has the same setup and he has no problems... so the problem must be you and not me". This is the logic used by people who can't actually explain what the problem is but resort to it anyway because they want it to be true.
I had chugging too when I followed some suggestions to get a spring that was less hg than recommended... when you press the gas, at certain region, it goes 'chugg chugg chugg' as if it doesn't know what it wants to do..."do i close do I open??? what do I do?"
This sounds like open throttle surging. In that case, that is probably the sound of air escaping your intake, not your bov opening. If that is your bov opening while you are accelerating, then you've got something else going on. If this is after you've let off the pedal, this is open throttle turbo flutter. Again, it is coming out of your intake pipe, not your bov unless you've got plumbing issues. That is the sound of the compressor chopping up the air.
Unlike twin turbo guys, big singles have a bit more audible resolution on the spool up, spool down process and I can clearly hear it through my window due to the turbo being on the right and my bov on the left so it is easy to differentiate what is what. Some people can't tell the difference between pressurized air escaping the intake pipe when you lift and the air escaping the bov. The compressor wheel doesn't make a perfect seal with the housing and when lifting off the throttle, pressure can equalize going out of the intake rather than into the engine or out the bov.
I keep saying the same thing because nobody has ever presented any evidence or argument other than 'do I open, do I close?' that is the most scientific explanation for why a stronger spring is better at reducing surge that I've heard anyone tell and that is not convincing. Bov springs don't have their own personality, vacuum pressures influence their operation of the bov plunger. Once someone presents something worth responding to perhaps the debate could go further. I'm happy to be proven wrong but I haven't seen anything from anyone that suggests a heavier spring reduces surge.
