Ah, you have 'Singer Syndrome'. As bullit-proof as these puppies are, its surprising how much noise comes out of it and how much it sounds like a sewing machine. As you continue to explore the site and read the posts, you soon find the most accepted 'cure' is louder pipes. Not much help I know, but if you had it back to the dealer and they didn't go into a frenzy, I'm sure you just have the same clatter we all have come to mask with more noise. In the mean time, keep your legs against the tank as much as you can. It muffles it some...
...thanxs
