I would'nt bother with a remap on a diesel 6, if the car is every plugged into Mazdas IDS/WDS software for whatever reason any altered files will be rewritten and the ecu will be back to factory spec, this has cropped up a few times now on and it's caused nothing but trouble.
I run a Speedhawk tuning box because of this issue and i'm very happy with the results, no issue with the DPF either.
Dave