They shouldn't, esp not with the LME exhaust components. If the sound is coming from the turbos, you may have a lubrication/cooling issue or a leaky seal issue. Recently had someone suffer a broken turbine shaft on their front turbo, so should not ignore it. If the sound is coming from the BOV (have you done this mod?), that may be the tune. Which version do you have, V8/V9/V10? What oil/filter are you running?