Seven years, 255 posts, lots of pictures, and references from successful tuning threads from across the internet... and some people still didn't nor ever will "get it."
This thread is a microcosm of what goes on every day, in every field of endeavor. It's no wonder the abundance of Fail in this world.
Having posted two and a half years ago that I'd found the subject mod a perfect solution to my own issues with an '05 LGT, and now the happy owner of a new 2011 WRX, I decided to revisit this thread. It took longer to read than I imagined. That 05 LGT is still local and running strong, for reference, but my reading has to do with the present and my new WRX.
I will be doing this simple BPV mod to this car, too. It hasn't anything to do with cheap, however. It has to do with reliability and how I want my car to work. Virtually everyone I know, or whose history modding Subarus I track, that uses an aftermarket BOV eventually has a problem with it. The PROPERLY modded stock BPV, however, retains its excellent OEM reliability, eliminates any related boost leak questions, and more importantly, fulfills the function these gadgets were designed for in the beginning.
It isn't easy understanding how it works. It isn't easy even knowing why there is one at all. This thread is testament to that fact. The above post, #255, illustrates this perfectly. And to be honest, after these many hours today chasing references across the internet and reading every word of every post, I also know more than I did this morning. I knew it worked and I knew how it worked, but whereas before I had accepted the resultant mini-surge as an acceptable imperfect compromise I know now it is actually necessary.
The poster convinced himself his new, complicated, bling with springs, shims, bells and whistles is "great." He also wants that "tiny bit of surge," the very 'surge' so many other posters had hernias over. It is also 'surge' that not only has no effect on turbo reliability, but is an inescapable artifact of a BPV doing its originally intended job. Poster #255 arrived at the correct functional answer, but via a very specious route.
Why is that mini-surge good? Because while venting the pressurized air in the intake needs to happen, venting ALL that pressure, like most/all OEM BPVs, means every shift must start from zero boost again. ZERO. Ideally, we wouldn't have to vent one bit of that boost but practically we must vent enough to protect the turbo. The compromise is to find the balance between just how much boost we can keep to enable the best shift-to-shift power stream without compromising turbo reliability. That "tiny bit of surge" is in actuality not a problem, but the indication of a BPV working to the best interests of the driver.
The "$0.16 BOV mod," IMHO, creates a perfect BPV. YMMV, etc.