I just recently bought a 2010 Fatboy lo switched over from a Honda Shadow 750, I love this bike!! I have already had 1 factory defect (Rear Brake) fixed under warranty. As I am new to Harleys when I start the bike up there's another sound from the engine kinda sounds like a swishing or teapot boiling without the whistling sound and continues till shut off, I have 200 miles on the bike. I was looking at you tube today and another Fatboy lo had the same sound. But for some reason the same bikes on you tube that had custom pipes installed I couldnt hear this sound. Is this normal am I being paranoid after the 1st defect? Will this sound go away? I look forward to your replies! Was just thinking is this maybe the airfilter?, just curious as my other motorcycles doesnt make this kind of sound.