Grange Grover

New Member
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?
 

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