[Simply335]

hi guys, i have recently noticed that there is some problem with my car (335d) when accelerating from low rpms in 5 and 6 (autobox), car vibrates slightly (when reaching top torque i guess) then theres a weird sound like thumping rattle too, once revs go higher its gone but its annoying and worries me a lot :/ i have replaced both wheel bearings and rear suspension bushes but it is still there, my car was mapped few weeks ago and wondered if this can be an issue?!
i would appreciate any comments on this, maybe some of you have had this sort of problems? what was the cause? thanks in advance!