As alluded above a gasser 2.0 turbo won't suit your needs. Most gasser bolt-on turbos are sized to deliver something like 8-10 PSI at 4k+ RPM. For a diesel you're looking for more like 15+ PSI at 2500, totally different animal. Very different requirements for compressor and turbine sizing.
AAZ injectors are fine the way they are, unlike TDIs. The IDI engines don't rely on the nozzle for proper mixing the way TDIs do, the swirl chamber takes care of that. As a result the stock nozzles are quite large and will support virtually any achievable power level that the head can survive.
The stock turbo can be turned up a bit - you probably have a K14 currently which is a pretty good street turbo. It'll survive 18+ PSI without issue, though you're going to need an intercooler to actually make use of that.
The injection pump is the real place to be focusing - it's the "brain" of the engine. You'll never get anything more than what it delivers. Upgrading the LDA (boost) pin and playing with the max fuel screw would be a good first step, getting a built pump would be the ultimate goal.
As mentioned above
http://vwdiesel.net is the best place to find info on tuning / improving the IDI engines.
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