Is it chipped to start with ?, if so if it is a msd chip phone them with the number and they will put you right on settings needed.
As I said I'm not 100% sure on the ecu adjust as don't use these ecu's anymore, and my ecu doesn't have a mixture screw.
Fuel pressure is indeed std at 3.5 bar idle with vac pipe off and pipe plugged, with vac pipe plugged back in it will drop to around 3 bar.
tabetha