Sard fuel pressure regulator

[jos 4 age]

Hi,
When I bought my car it already had a SARD fuel pressure regulator mounted. Fuel pressure is about 45 PSI now, for some strange reason it is 5 psi higher than a few weeks ago, but I did not change anything on the engine Unfortunately I do not have the manual for this regulator, does anybody know how it works if I want to adjust the pressure ? Looks quite simple but just want to be sure.
( cannot downlaod the manuel from somewhere .. )

It looks like this :


What happens to the mixture If I decraese/increase the pressure ?
Since I use an Omex ECU which is callibrated on the dyno I dont want to take any risk.