320d black smoke on heavey accelaration

so ive seen 1 e46 320d 140k on clocks only problem im is its dumping black smoke from the exhaust under hard accelaration.



any ideas wat it could be the drive is fine no warning lights or anything just the smoke.

i heard that the filters or split pipe work could cause this??



its a good deal and thought if i get it i can get it fixed that wont be a problem as i already have a 2nd car.