PSI Powerbox adjustment?

Hi, does anybody know if the PSI Powerbox by Motorsport can be adjusted to give even better performance?
I have opened mine up by removing the 4 screws on the lid and can see a red & green LED and a small (adjustable?) screw type potentiometer. I haven't had the nerve to turn the screw as I don't want to mess it up or cause engine damage.
What do the LED's signify and when should they light up?

Go here............ Psi Power Box - TDIClub Forums

& read all the thread ..... POST No 10 is MOST ENLIGHTENING!!!!

Excellent, thanks for that.