I have a 2bennet stage 1 ecu and nuespeed intake. In fourth and fifth gear at full throttle regardless of my rpm the boost bounces up and down instead of steadily pulling harder. The boost maxes out 18 psi but will bounce from about 13 to 18 in 4th and fifth. I have 3 extra external wastegates that I tried to no avail. Any idea what could cause problems? N75 boost pressure control valve is brand new and my dv is good aswell.

Thankss
ANdrew