Put the muffler back on the bike. And listen to the beauty. Its a good idea to get the bike on a dyno and make sure it isn't running lean. I had mine done and it all checked out fine. I also did an "air restrictor mod" a few months ago, which is basically pulling the restrictors off. I live at 5600 ft and often ride at 7000-8000 ft. The bike comes from the factory tuned to sea level so all these mods are actually helping the bike not to run rich. According to the dyno the bike is running really well.