My AGU with K03s was also knocking back to 5psi when I was at full chat in 3rd, 4th and 5th, although I did have that peaking at 22psi, Forge actuator, yellow spring.
So what do we think is doing this? N75 not being able to adapt far enough for the increased boost on a map not designed for it? Mine has a stage1 k03 map on it.