It does sound like it needs to have a constant clear out of the carbon build up in the EGR, DPF and Turbo.
Carbon builds up in town driving and only really has a chance to clear when the power is applied.
When a DPF regenerates it produces smoke and you will also notice the engine temperature may rise. This is normal and needs to occur more frequently to keep the DPF clean otherwise it will cost a fortune to clean or replace