.45 could be from a stuck closed airmeeter box too though. if he's not getting enough air to compress in the turbo, it'll certainly limit boost.
you could rig a probe into the turbo intake tube, and see if it's operating in a vacuum, or at atmo. heck, I'd just pull the air cleaner, and jam a pipe in there to hold the blade open, and see if it helps!
or temporarily pull the intake tubing off the turbo entirely and see if the car performs better or not.

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John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

My drivers:
1987 190D 2.5Turbo
1987 560SL convertible
1987 190D 2.5-5SPEED!!!

1987 300TD
2005 Dodge Sprinter 2500 158"WB
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!