Anyone used one of these? The local dealer can get me one for $40. Seems about average cost wise but will it help my bike pass noise? Here in CA the limit is 96dB. Went to the local OHV park last week. With FRESH packing (~1HR) and 6 discs my bike tested at 100.8dB. With 3 discs it tested at 98dB. Still too high and it's really choked up at that point. I was thinking about getting the insert to get it down a little more. The catalog claims it'll reduce sound 2-5dB. Does anyone have any info on these quiet inserts?