I haven't found information on diesel testers.
About the ASNU fsi/gdi box (gdi meaning gasoline direct injection nothing Diesel) I also found this technical info:
http://www.asnu.com/downloads/low-pressure-gdi.pdf
All great and well and indeed testing abilities at low pressure are also important, but besides that it is a big bunch of BS, fellow audi enthusiasts on an American forum have found that leaking FSI injectors from our S6 and S8s will only start to lose fuel above 30 bar system pressure.
I've got some hydraulic equipment that can easily be reduced to produce 100 bar and filled with another liquid. I'm slowly leaning over to getting 10 adapter bungs machined and buying 10 borosilicate lab flasks and a pwm driver board.
I just wish I could outsource the testing