Fitted a new throttle body and did the air flow calibration, before it went into the garage to have a replacement rear diff (from Bell Engineering) fitted.
Massive difference to how it drives now, so much smoother and lot less noise.
I've had a stage 1 remap done on my 08 Td4 and am pleased with the outcome. Slightly better fuel economy but more impressed with torque at lower revs. The only thing I was warned about was the gearbox not being able to handle higher torque...