It all depends on what you want ......do you want loud or just mellow? Since you said that you don't want to jet it then that case your limited to a slip-on. Muzzy's are good for Kawi's ...btw if you want loud..i would suggest a D&D. I have a Carbon Fiber D&D Slip-on....also your not going to get a drastic horsepower over a slip-on, just a couple or two horsies. Slip-0n are good for noise and weight reduction.......however, if you want to increase horsepower then a full exhaust is the way to go but the downside is that you have to get your carbs jetted. Good Luck on deciding.
Just wanna throw my .02 worth in here. I would highly recommend the Micron slip-on. I have one on my 9, in Carbon Fiber and the sound is awesome. Not gnarly like the Muzzy or even the last D&D I had on another 9. I did the jetting 'cause I'm crazy like that and it bumped things up by 12hp. The slip-on alone will probably only yield 1-3hp. Have fun!!