Do the BOV's operate on ambient pressure or the on the pressure inside the hose?
 

In other words:
If you apply "X" amount of vacuum to the small nipple, the valve opens and air flows between the two larger ports.

Now, if you apply "Y" pressure to the larger ports, does it take X-Y amount of vacuum (or pressure) to open the valve (operates on internal pressure), or does it still take "X" amount of vacuum to open the valve (operates on ambient pressure)?

x

double post

its late... im lost Jonski... :D

no....there is a spring involved, and it works with the small nipple