Management

G60 Digifant I ECU and loom with custom programming and bigger 300 or 440cc injectors. This is probably the simplest VW efi to run on a turbo 16v. Get the ECU, wiring harness, CO potentiometer from a Corrado G60. Your factory throttle switches and 02 sensor can be retained. You will need to install the g60 CO potentiometer before the throttle body but after the intercooler. For coolant temp sensor you can run a G60 20mm press in fitting but you will need a flange from. This allows you to use the factory digifant blue coolant temp sensor with proper resistance slope. A knock sensor is also required, as this is very important when running Digifant I. You will also need a chip for this application and injectors based on the chip being run (440cc, 480cc etc).

Standalone engine management the likes of Megasquirt, DTA, Motec, Haltech, Emerald etc. This is where things get fun, but also expensive. The good thing about a full standalone system is that as your application changes, you can make changes to take full advantage of those changes. This can ensure you maintain reliable AFR and timing throughout the rpm and load range. Much larger injectors can ususally be fitted, which allows quite a bit of power to be achieved. Some have quite a few features which can make your life easier (boost control via the ECU, 2 step rev limiters, speed/gear based boost control, limiting rpm below certain speeds, etc). The downsides are ususally cost, time for install/tuning. I'd say if you plan on more than 300 reliable bhp, look into stand alone. Not saying it cannot be done on the other methods, just as a guide.

Delivery

Most stock VW fuel pumps good for just over 250hp of fuel, but an inline Bosch or Walbro in conjunction with the stock pump is the safer option if looking for more power. The 16v K-Jetronic/KE-Jetronic (KR/9A) fuel pump supplies fuel at a higher pressure than the digifant fuel pump, due to the nature of the injection system. The supply fuel at a maximum of 7-8 Bar (apparently), so work very well for turbo applications

As a general rule of thumb, depending in your target output, you should choose your injectors with a flow rate of the same cc as desired output in bhp. You don't want to be using injectors that run at 100% as they are more likely to overheat and reduce their life, so ideally you want to be running them at a maximum of 80-85%.