just got my 07 bf a week ago, 100k on the clock, didnt hear any noise whilst test driving it, a few days later im hearing this clunk from the rear end only in 1st and only taking off slowly, sounds like something is knocking on the diff. its got warranty which covers diff but not all components. Taking it to my mechanic mate next week who is super good at what he does and completely trustworthy......see what happens! ill let u know. my noise sounds pretty similar altho not getting worse but only had car a week!