Ok so I just bought a new axle back WS2 system to replace the old Apexi N1 exhaust I was running before. The N1 was starting to get very annoying and just wasn't cutting it anymore. So I bought the WS2 and bolted it up. Checked to make sure everything was tight and that every thing cleared the exhaust. The muffler is big but there was still at least a half inch clearance all around the muffler. The tip looked nice and the sound was a bit louder than stock, but still quiet. So I let the car warm up and I take it for a test drive. Well at about 2,500 rpm I hear a faint buzzing/humming sound. then goes away above that until 3,500 rpm when it comes back even louder. Its not a banging sound, more like a quick tight vibration. Its even more annoying when the car is under heavy load in those rpm ranges like when I'm going up a hill. And if I stay right at 3,500 the buzzing is constant. Sounds like its come right near the passenger side rear section right above the muffler. I made sure my rear bumper was tight and I even took out most of my rear panels trying to find the noise. I checked the muffler before I installed it to make sure there was nothing rattling. Has anyone else had a problem like this with the WS2 exhaust? My N1 didn't cause this much racket.