it must be the setup - since you changed the cooler its running more boost on the stock actuator.
Try taking the spring and the ball bearing out and then testing how much boost it runs (put the screw in 2 turns and lock it in just to seal it off) and that will give you a indication on the minimum boost you can run.
If you do that and it runs the boost you want then leave it like that untill you plan to turn the boost back up again.
These are great controllers.. i run one on my rb30det with 317 rwkw with external gate, the boost curve is straight as.. so yeah try that and see what it does then let me know.