Same here - 20k old motor, factory 2nd cat, magnaflow first.Mine generally does 5.5psi. The highest I've seen mine is at 6-6.2PSI floored from 0 to 100. I have not seen any higher than that.
Brand new rebuilt engine but on factory cats and factory exhaust. I'm wondering if it's my restrictive exhaust...
Topped out at 6.2 under load, occasional spike at shift (doesn't really count).
I'm not concerned with the lack of .8, but makes me want to try a new 2nd cat/replace the old exhaust/2nd o2.