The term PSI is a bit misleading the way we colloquially use it. When we use the term "PSI" we're actually talking "PSIG"(manifold/charge pipe pressure with "0" being atmospheric pressure.)
Unless it is the Cobb guys talking in relation to Boost mean abs and Boost mean act, that's PSI. That's something I see people get confused about when looking at Cobb logs. They think 28psi means 28psig and that's not the case.
"I'm not surprised you get along well with all the other neighbours. If you put fifty children with Down's syndrome in a room there is going to be a lot of hugging." David Thorne