Originally Posted by Suncoast Rod Shop

Ok I see what you're saying now. Very interesting information!! So do you think instead of -10 return I should step it down to -8? I'll have to re-check where the vacuum line to the reference port on the regulator is. I do have a vibrant vacuum manifold screwed to the firewall that's feeding/supplying vacuum to assortment of things so if the vacuum is coming off that going to the regulator - you're saying it's not pulling appropriate vacuum and needs to be plumbed directly off the intake by itself?