ive got the exact same problem mate (bamk2 6 spd) 36k, I had mine on the hoist the other day found no major issues, a very good diff mech told me its most likely to be a number of small thing that make up this noise throughout the whole drive line including gearbox (could have slight wear), but if it helps ever since I lowered my car more I think the noise had slightly picked up so could be CV joints and theres kno real way of knowing unless u pull it 2 bits im told so yeah.. let me know wat u found dude, because I mite have to do somthing bout mine aswell cheers nick