If I remember correctly the stock setting is at 2.2bar(~32Psi). My setting adjusted to 2.5Bar(~44Psi) after dyno tuned.
We're starting to see more stock FDs having low flow problems from their original pumps. This is because the original stock fuel pump starts to show their age with time (~13 years). Better get your original fuel pump replaced or upgrade a better fuel pump. Try to get a Walbro(341).
Also, if u dont know when was the fuel filter was replaced, put a new one on. A must done for every other year.