WOW! Just took out the new dual slipons (w/quiet core & spark arrestor installed) w/digituner out for its maiden voyage. Did 63 kms of back roads so I was cruising between 60-80 kmh for most of the ride and WOW!!My ears are ringing. Im pretty sure I will be using ear plugs from now on. I knew what the muzzy would sound like when you are riding behind it or standing around it because my buddy has them for his Outty, but I never realized how loud it is when riding it. It sounds awesome, but DANG my ears!