I know there are a number of factors that are involved in what gives an exhaust it's own distinct tone but I wanted to know this answer more in depth when I decided to put a 'Slip-On' onto my 600rr. The obvious answers are some have baffles removed and some are aftermarket. When I put a Scorpion slip-on on my Street Triple, it was VERY loud and I never thought I would say it but after an hour of riding it, it became obnoxious! However, when I put a Scorpion slip-on onto my 600rr, it sounded a little louder but not much more than the stock exhaust. I was actually a little disappointed if I'm being honest when I first fired it up. I just came to the conclusion that maybe it was where each exhaust was located (under the seat for example, so all noise is behind me) or because it wasn't a full system I'm not an expert... just wanted to know the thoughts from others.