old problem with the fuelflow. the boosters are angled and some pixels of the tailend and fusellage are touching/clipping into the corestage (NO PARTCLIPPING ACTIVATED) sometimes, the corestage sucked fuel from the boosters and sometimes it worked perfectly. the decouplers ensures no accidently fuelflow from the boosters to the corestage. i knwo it's weird, i just had to increase teh distance between booster and core a bit more BUT that would look ugly.