15G Wastegate Spring

Im looking into maybe replacing my stock wastegate actuator with one from kinguwana, looks like they have a bunch of different spring rates (.3-2bar)...does anyone know what stock is? Do I want a stiffer spring or same? Thanks

http://shopping.kinugawaturbo.com/turboadjustableactuatorvolvo850s70td04ltd04hl3spring101215bar.aspx