Ok Olds, my Vac is right at 5" at 1200/idle. The PV is wrong then... I think the stock PV is 4.5 which is the one I believe in the carb right now.I have a 3.5 too which I will install probably today. I think that you have a good point... + elevation here is about sea-level. The other thing I found yesterday was the NEW Holley reg (w/bypass 4-9psi) is leaking a little at the base of the pressure adj bolt... I teflon taped the bolt & it stopped. It is my understanding that the top of the reg should be dry.... the diaphram is fine (no holes) WTH????? Yeah, it's a street car... I guess.. It's more like a drag car w/slicks & license plates. The state of Oregon would not call it a street car... Lol!!