try some of the wholesale s/c dealers then can all get that kinda stuff for cheap. it goes from the discharge tube to the inlet tube. i prefer a vortech mondo BOV/by pass valve.
The bypass valve bleeds off the boost pressure in the tube when you come off the throttle so it does not force air the wrong way through the blower.... You could use almost any manufactors bypass set-up as long as it works with your pipes, they are really needed at around 8psi.
Well you don't get the sound on a Mass Air car unless you have a intercooler...
On a normal MAF set-up the air is routed back into the intake tube since it was metered air that the EEC read, on a intercooler set-up (like a ATI procharger) the air meter is after the blower so it is vented into the atmosphere like a turbo....then you get the noise