you are correct, the leaky stock BOV will eliminate surge at the expense of making less power. you can adjust the boost control to not drive the turbo into surge.

 

Changed to the white spring and it did little, if anything, for the surge problem. It does release much easier for normal driving so I would recommend the white (-8psi) for those on stock cams/intake.

When I replaced the spring there is no way to add a bottom port. The underside of the diaphragm is essentially the dump path for the valve when it opens. In looking at the TurboSmart kit I think I can at least simulate to see if the concept of bleeding the top port works. If I unhook the vacuum line to the BOV it should open if the boost pressure on the valve face can overcome the spring force. I will probably test this theory tomorrow.

 

if you've got a recirc bov or are running speed density, the -3psi (hot pink) spring is by far the best driveablity IMO.