I just put this exhaust on my 2011 ZX6R today and I went for a ride right away. At first, I didn't really like that it looked a lot like a cone, but then it grew on me. It looks so much better and It's so much louder than that stock tin can and I can tell that there is a weight difference. Installation was pretty easy except for the top bolt on the foot peg, which was a little tricky to tighten but not too bad. The screw on the actual cone did not tighten all the way for some reason. No matter how much I tried to tighten it, it would just keep spinning so I just tightened that bracket bolt where the exhaust goes in and left it like that. Not sure if thats how that bolt is supposed to be or not. It didn't feel too wobbly so I hope it stays on lol. Other than that, this exhaust is cool and it's loud. It roars out on the street and other traffic can now hear me coming.