For the mods, you can start by putting the 1.6TD boost pin in the pump, (from MK2 1.6Turbo diesel models), you can also make a boost bleed, which will allow you to set the PSI you want the turbo to shoot into the intake, then you have to adjust the fueling to have enought with the boost you have set.
Those are the basic modifications that you should do on an AAZ engine.
Next step, the intercooler... Try to find a good intercooler to fit on your engine, so you can cool the air flowing into your intake.
After those mods, its probably time to upgrade the pump head diameter... Stock you've got a 9mm head, that you can replace by a 10,11 or even 12 mm...
Actually I'm running my 305 000 km engine with a TDI 2001 intercooler side mounted and 20 PSI in the intake, i see smoke behind the car when i hit the pedal to the metal, which means he has a little bit too much fuel, but it's ok... I've changed my head pump for a 10mm, and just to give you a hint on how it does, I've run a 16.6 sec at a 1/4 mile on september 15th, and the car wasn't as powerful as it can be late nights, when it's colder outside :wink: :twisted: