k&n panel filter is a good cheap mod on these, performance ford done a tdci tuning feature and it gave a 5bhp increase.

Personally I wouldnt be remapping one of these, the delphi injectors dont have the best of reputations and ive heard of injector problems after using tuning boxes.

But if you are going for a remap, its hard to look past Bluefin - ive been out in a bluefinned 1.8 TDCi and there was a noticable increase over standard.