The main concern for the RS3 that there is no enough researches and feedback about it!
When I contacted VAG FUELING SOLUTIONS they said they didn't test it in big setups yet but they expected that it would achieve 600hp!
How you can expect something you didn't test!
I found the below injectors long time ago and it has been tested by them up to 700hp+
https://www.tij-power.com/product_info.php?products_id=493352
As per Tij-power, it is Conti Injectors; but there is also concern about it that the injectors mount should be a little bigger.
They confirmed that it's very simple and easy without any leakage but I don't think I will be the first one to try.
Anyway, just tried to share all what I have.
Wow 1500 for a set of injectors!