Boost pressure fault

Howdy folks. Late 2015 model 150bhp 2.0tdi no ad blue.

If I push on over 3k rpm the car feels like its running out of steam. If I keep pushing it will go into limp mode and throw the fault p0299 (boost pressure regulation range not reached)

Ever since I got the car 6 months ago it is very smokey on hard acceleration taking off etc. I have a feeling the dpf has been removed/mapped out before I got it. It has high mileage.

Drives pretty normal the rest of the time. Decent acceleration under normal driving although I have driven a few other cars with the 150tdi and they have felt a bit more lively. They were also newer and lower mileage!!

Just wondering if anyone had something similar? Anything to check out or anything?

Possibly n75 valve but would be expecting it to be a bit more inconsistent?

Thanks