Aha. So the bypass on on a centrifugal blower is essentially the BOV. Now I can see where your coming from. Makes quite a lot of sense now.

Then how would a bypass on a pd style blower be routed? I'm assuming that it would just be routed in parrallel with the blower.

they are one in the same mate, the only difference is that bypass valves are designed to always open under vacuum, many BOV's will not. At least thats my understanding.

In between the blower and the MAF mate. Vented directly to atmosphere, as hasnt passed the MAF yet, therefore ECU doesnt even see it. I did have a hose on the valve, just ran up the front of the car... pretty much so it looked like it was going somewhere lol.

The valve was open and venting whenever the manifold was in a vaccum state. Idle, light throttle, deceleration...tended to hit atmospheric pressure in the manifold at around half throttle... any more than that and you start building boost... but boost built almost immediately at full throttle and 2750rpm and above.

Lol, i cant think for the life of me how the bypass/blowoff on a PD works??? It would have to vent directly from the manifold or the blower itself wouldnt it???

Probably because they have such stiff springs in them.

I know next to nothing about positive displacement superchargers (the ones mounted on top of the intake manifold Im taking it), but I cant see why they would need a bypass as they would draw thru the throttle body not blow thru like the centrifugal ones. Does this make sense?

yeah PD dont use bypass valves, some eaton style screws will still have bypass like the YT kit for boss engines.

The original spring that comes in the BOVs is generally too stiff for this application - they're made for turbo applications.
But luckily most brands, like Turbosmart have springs kits avaliable specifically for this application (for Centrifugal Superchargers - see http://www.turbosmart.com.au/index.php?id=47 for the listing on them).
These are avaliable from CAPA (see http://www.capa.com.au/prices_turbo.htm for pricing).
Since I've got a Type 3 Dual Port (http://www.turbosmart.com.au/index.php?id=48) all I'll need is teh FG-BVS-SPCS Centrifugal Supercharger Spring -Red. Fits Vee Port and all Type 3 BOV's for $20.00 from them.