This thread is pretty much it on this forum. There are other threads about the bike on ADVrider, but this one is the most comprehensive. There is a wealth of information at kawasakiforums.com; if you search there, you'll find your answers. I think the 2 Brothers is known as being excessively loud. There may be other "quiet" tips available for it, but if you really want quiet, you may need to look at another brand of exhaust. Depending on you skills/resources, you may also be able to fab your own tip. Peak power is at about 8500 RPM, so you should feel a reduction in power as you approach redline. That's not to say you may not have a tuning issue.