I could never go turbo over supercharger, I prefer linear power and it makes the car more predictable as well.

 

Bypass the clutch switch and see if it still happens.

 

Whats interesting to me, since I closed mine also, is I’ve got mine all the way out, basically just past the o-ring, and I still get surge on cold start (even though the hks doesn’t do that for me), but it’ll just go away all of a sudden. And with it closed, it’s so quiet I can’t tell if its surging during low rpm cruising 😆
I can hear it surge during shifting, but it’s real quick, doesn’t last long. And I’m pretty sure the hks bov did the same.
Didn’t make a change to driveability much and the car still fells great during pulls. Since I’m on the big pulley I don’t think I have to worry about overcoming the spring pressure but idk.
I’m kinda glad I have this bov though because I had installed a Koyorad Hyper V-Core radiator and I don’t think I would’ve gotten the original bov to fit, I already had to trim the fan shroud a small amount to get the turbosmart to fit. I could probably go slightly further on the shroud and adjust the bov hoses and get it to fit, I’m just a bit afraid of going too far.