[ceslaw]

I also put on a set of Stainless Specialities side pipes on about a year ago and noticed the same thing. Sort of a metalic flutter sound when decelerating. Not really that loud, not a backfire. Car runs great, so can't see any reason to be concerned. It was not there with the stock side pipes, but they were so loud I doubt i would have heard it anyway. By the way, the Stainless Specialities pipes are really nice.