I noticed heading up Loveland Pass in CO this weekend that at 10k ft I was only seeing 10psi on the boost gauge full throttle at 4.5k (I normally see about 13psi at 5400 ft). Is this limitation due to boost control or the limits of the turbocharger.
I have a turbo miata which when using wastegate control only will deliver a constant psi regardless of altitude on my boost gauge. When I go to closed loop map control (via a link ECU) the gauge psi goes up with altitude (about 3psi per 5k ft).
I would expect the WRX behavior to be similar to the miata.