The torque spec is 25 Nm, there is no specific sequence. I snug them all finger tight and then alternate top and bottom from cylinder to cylinder starting in the center and working outwards. Sort of, 3 top, 4 bottom, 2 bottom, 5 top , 1 top, 6 bottom etc, get then all pretty tight and the put the torque wrench on them for the last turn again starting in the center and alternating You basically want it tightened down to spec as evenly as possible.