If it's the one that connets to the bottom of the diaphram, it's for quicker release. You connect it to a source before the TB and when the throttle closes the BOV opens a little quicker because of the extra pressure under the diaphram. The downside is under high boost the valve will want to leak with the extra pressure forcing it open
I know the mini-mopar guys are using the similiar setup, somewhere on the web there's a site detailing putting a solenoid on the line going to the lower nipple so you can have quick release for daily driving and still avoid the leaking under max boost
Rob_O