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Bypass valve install - FYI

Scott M writes on the bypass valve install
>Please also note, that the bypass valve REQUIRES boost pressure to be
>applied from the intake manifold to this "vacuum' connection on the
>bypass valve in order to hold the valve closed as the boost rises in the
>intake system/manifold. 
>I found this out, inadvertently while installing the bypass valve on my
>car when I only had the one connection on the bypass valve connected to
>the pressure side, without connecting up the intake side and the small
>>vacuum connection. I needed to run out to the parts store to get some
>hose to finish the installation, and found the bypass valve would
>immediately blow open as the boost went above 1.0 bar abolute. The car
>make this very nice loud whoosing sound and basically barely ran as air
>was blown out of the valve. (nice rich mixture with no boost)
Scott et. al.,

I measured several valves at my shop a while ago.  The valve with upper
connection open to atmosphere (sea level) it will crack open at 6psi.  The
sport quattro valve will crack at ~7-8psi.  The sport quattro valve uses a
slightly stiffer spring and has a thicker diaphram.  It also costs almost
twice as much as the stock 20vt. 


Scott Justusson