Stock pressure is 3bar at WOT, so it should be set with the vacuum hose disconnected. I would advise noting what it drops to in idle and checking this say once a year, as the FSE valves are notorious for not holding fuel pressure properly........one of the reasons I use a SARD reg on my car, the FSE was binned years ago for causing running & mapping problems.
Sorry for the above info, i hope you have one of the few good ones
yeh. fse = nasty.. i use a sard aswell.. but even those are being copied by the chinese.. so beware of imatations , you should really set it via a dyno or wideband to get your mixtures right.