I cut off a part of the red cap to allow pressure to be relieved before the motor comes up to pressure. I also tape the ematch to a 1/16” dowel to hold the ematch at the top of the motor and then use the red cap to hold the dowel in place. All of my two stagers have been 38mm or larger. I don’t know that the dowel would fit in a 29mm, and I wouldn‘t be nearly as concerned that the thrust from the booster would cause the ematch to move away from the top of the motor.