10 psi spring, all I could find when I ordered it. That spring is rated for 19 in/mg at idle and the car pulls a solid 21-22 at idle. If I go stiffer on the spring, it'll be at the proper rating for my idle vacuum, but if anything it'll need a lighter spring to ease the stall and let it activate easier.
I took it out for a spin and wot it blows off as it should, but under light load (3-5) psi there's a slight delay where you hear the compressor stall, then it blows off. That delay is why I'm thinking it needs a bigger, dedicated line. I went and bought some 5/16" line so I'll swap that in when I have some time and see if that helps.
One thing I will say is that the valve sounds waaay different than OEM. Much cooler sounding.
Last edited by RcrsWetDream; 10-08-2012 at 09:30 AM.