It's not IMPOSSIBLE, but it's bloody hard.
I was having boost issues in the Stag, was very low and inconsistent around the 5-7psi range, even swapping my R32 actuator in didn't help, turned out the cat had collapsed and was blocked, causing the drop in boost. Bashed it out, got 10psi back (actuator pressure) and then dialed it back up to 15psi.
I also don't buy the "exhaust gives you 2psi" shit, pressure is pressure, just because you have a more free flowing exhaust doesn't make the actuator give you an extra 2psi. It may get there faster due to better flow which might make it briefly spike over whatever your actuator pressure is, but it's not going to hold it to redline.