Boyesen's revolutionary dual-stage reed design delivers more usable power than stock. Your original one-stage reed operates most effectively only within a narrow RPM range. Boyesen's one soft reed on top of one firm flow-through reed gives you a wide range of intake control, plus increased intake velocity. Your original reeds can't possibly duplicate that performance. Dual-stage reeds. Minor change give major HP improvements. Faster opening and closing. Greater low pressure (low-throttle) response. Greater velocity and flow area. Longer overall life. No engine damage if broken.