Interresting!.. so you have done nothing to the front hose, and put a t-piece on the rear one and hooked this up the BOV....
So when you step off the gas and the vacuum under the butterfly will "assist" the building preassure in the intake-pipe to open the BOV?
How does this affect the original function of the mechanism in the pump?
It's obvious that your car works though... Muddy in Panama?