you would be surprised how much performance is helped with good tight packing. other than that all you're going to do by sealing off part of the silencer tube is increased noise. "sound faster" please don't be "that guy" you can shorten, or lengthen the stinger tube OAL to tune power/rpm , but you won't increase the power. the packing just absorbs noise. it doesnt degrease flow unless there is a lack of, or loosely packed packing.