how to set up the bypass valve?

vented to the atmosphere will be louder... depends if thats what your after. As far as the air meter... if it "reads" the air before the bpv, then you need to run it back to the system, if it pops off before the air sensors then you can do it either way. If you shoot that air off after the sensor has already registered it, then you will run rich. Like rich enough to kill the engine I think... but... I'm not a mechanic. Just my best stab at it.