An fcd with no fuelling mods is a recipe for disaster. If you want to keep the car standard then do that - put the 1st and 2nd gear restriction back in and that should lower the boost enough to avoid fuel cut, however differentcars react differently. Any slight modification to the intake or exhaust systems can have an effect on the boost levels the turbo will run at, colder weather also makes a big difference. The first thing to do if you do want to mod the car a little is to get a boost gauge to see the boost you're running, if it is overboosting I would then advise on getting an uprated actuator as that will help control the boost better than the weak standard actuator.