The PV does nothing at idle since the mains aren't flowing! I've run as high as a 10.5 and as expected, it has no effect on my idle AFR at all. But it was too rich at light throttle because it opened too soon.
What makes it even harder to tune is the 8" at idle, but 15" at cruise. Most street engines with small cams show high vacuum at idle which goes down at cruise. It'll never be perfect, but Pro Stock-level concerns to the contrary, I think I've made it work reasonably well on the street.