Vibration from rear end

[Boosted Man]

Good day, after doing software on my E90 320d I have a split second vibration from the rear end of the vehicle when flooring it. My brothers 120d does it aswel after software. I feel it's related to the added performance. Has anyone experienced this and found a solution. Please share.

 

[TurboLlew]

When last was the diff serviced? Check for play in the mount as well.

 

[Boosted Man]

Not sure when last the diff was serviced. Got them both recently. Both cars were inspected quite well recently and all the rubbers /couplings/ bushes look perfect.
Do u think a. Diff oil change will solve and if so what oil is best for the diff