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I recently purchased a Turbosmart dual port 50/50 BOV and was wondering how one would go about getting the right stiffness of the spring?. Thanks!
I have the same valve, just installed last week. I read somewhere the Hard setting is for sea level elevation and the soft setting is for high elevation.

here is some info from their website on adjustment.

The aim of the adjustment on the Dual port is to make sure that the piston is hard closed at idle and that the piston closes fast enough
to minimise backfiring and not stall the engine. In most cases, the cap is in the correct position from factory but with certain engine
modifications, springs changes are required to tune the performance of the valve to the turbo system.
Adjustment to the BOV is made by rotating the cap. To increase the spring force on the piston, rotate the cap clockwise in the direction
of hard as marked on the top of the cap. To decrease the spring force on the piston, rotate the cap anticlockwise in the direction of soft
as marked on the top of the cap - CAUTION - Do not rotate the cap beyond the O-Ring groove. Once it is confirmed that the piston is
fully closed at idle, perform the following adjustment procedure.
 Start with the BOV cap at the maximum soft position (The O-Ring should be completely covered by the edge of the cap)
 With the engine at idle the exhaust port should be closed off by the piston – the piston should be hard against the seat and not
floating or moving
 Free rev the engine and back off quickly, the engine should return to normal idle speed – if the engine drops below idle or stalls
increase the spring tension by one turn
 Repeat this process until the engine free revs and returns to normal idle speed
 Test drive the car and ensure that when decelerating or changing gears that the engine has minimal backfiring and no stalling. If
backfiring is excessive or stalling is noticed then check all connections made during the installation, otherwise increase the spring
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