You didn't say whether manual or automatic; I get similar results on my S70 T5SE automatic, and like you mention in your later post, have spiked at 17 plus under rare circumstances.

My ECU seems to step-up boost depending on conditions. From zero, typically I see around 4psi sustained / 9 spike until the car is moving, then 9psi sustained / 14spike.

I spiked 17+ twice under identical conditions in exactly the same spot: already doing 50 and "dropping the hammer" to pass a truck on a two-lane rural road. This is actually a little scary as the torque steer just about wants to flip the car onto its roof, and in just a couple seconds I'm already well above of 80mph.

BTW, located my boost gauge in the ashtray bay, just ahead of the shifter.