Make it breath better.
I did the injectors, pump timing, K&N, Exhaust, and increased the boost to 18PSI.
Huge difference!!!
Cheapest first:
Adjust the boost by winding the waste gate actuatng lever as far as it will go. Fit a cheap boost gauge ($20) to help set it up, it should get as far as 18PSI and no more, you run out of adjustment
Exhaust, take it to a shop and get them to cut the old silencers out and weld in some straight through ones($120). Ones you can see right through,ie no bends and switch backs inside.
Then fit a replacement element K&N that fits the standard air box ($150). Not a POD.
Take it to a diesel mechanic, tell him your not worried about smoke or fuel economy and get him to play with the pump.($112 Labour only)
Injectors are good to replace, but very expensive to do. About $60 per injector and the $$$$$$$ for labour. Around ($400 all up)
Makes a difference when they are set top the correct pressures!!!
It made a huge difference to mine, it powered 32 X 9.5 Simex centipedes fine all the way round the south island for a long time!!
Cheers all 
more power from a 2.7td.....
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plumb an intercooler into it and a pod filter and should go much better, not tooo costly if you have a bit of knowledge and do it your self