chip or box?

tuning boxes are popular on other forums, but I personally don't like them. It's basically a piggyback, or device to fool the ECU and give it different values. A chip is pretty much always better and is plug-play. Soome tuning boxes requires you to do some end-user setup and tends to not be as efficient. A chip, while giving more fuel, doesn't raise the boost, so this alone causes you to lose efficiency.

Because the ecu can't see the real values, diagnostics are harder, and may cause drivability problems. If you search, you will find that chips are much more popular, and it's for these reasons.

where do I buy one of the chips?

do a search for rocketchip or kermatdi

rocketchip sells chips for lots of various cars and kermatdi also sells nozzles and turbos

2nd these two seem to be the most common diesel chip vendors. the market is small, but its there

Jeff at rocketchip is the way to go, very nice power, and Kerma for the injector nozzles, nice set up.