MBC problems.

I installed a MBC but it won't raise the boost past 13 psi. This is what I normally boost at. It couldn't be a BOV problem could it (yet to upgrade)? I hooked it up just like it says here. http://www.belitski.com/cars/talonmods/turbo/vfaqhallman.html
I also plugged the bottom nipple of the BCS. Is this a common problem or do I just need a better bov (I thought mine would at least hold 15).