Yes, that's what I was counting on, everywhere the flow was given at 3Bar pressure, so I knew it would be very similar to the stock injectors on the RS4, but I don't know the exact calculation. How can this be calculated please?

We do know that intercoolers will be next in line for an upgrade, but that's for another time. The K04 was chosen so that turbochargers wouldn't have to be addressed in the future.
So what is the possible safe performance for k04, BAM injectors? The other components are original. Thanks.

Fitting K04's on a S4 is a waste of time anyway.

Because to use them for full potential you need to:
1. Build the engine (at least conrods, they bend after 1.6 bar).
2. Get all new intercooling.
3. Get a full exhaust system incl. downpipes.
4. Upgrade the clutch.

At this point you might as well fit bigger turbos. If I only had $1000 every time I got a tuning request with "I have a stock car with K04's" lol.

Sort of. Turbos bigger than K04 generally take too long to spool (and you have to do everything you said). I still think K04s are great, you can't beat them for a very fun torque monster. But yes, they require a ton of supporting modifications.