By nature, at part throttle, your BOV should leak if you're SLOWLY accelerating because it's actuated by your intake manifold pressure. If you've spooled your turbo, and you're rolling off the throttle, your intake manifold will contain less pressure than your intake, so the bov will vent. At lower PSI, this BOV would be less of a problem, but at 21 PSI, it breaks stuff because it chatters like crazy.

I'm not externally gated, but I've ported the internal gate to 34mm, ported the exhaust housing to 7cm. It still boost-creeps like crazy. It probably wouldn't be so bad if I got an external gate or a bigger turbo. I'm just using a TD05H16g Mitsubishi, and it's probably my biggest restriction. I'm planning to upgrade it and bolt this one on my Colt.

You sir, are using a 67 trim monster. it will have way more potential than my dinky little turbo. Looking back over your mods, I think I underestimated that turbo.