Ahahah at the end u find another solution i see :)

Thank you, just about to write you a message to inform you.
I want to keep all my mods using the same license, so I decided to build things from scratch.
Another reason is that I found "hacking" the storage tanks as ducts/pipes have the problem of dropping pressure a lot over a few "pipes". Keep using pipe type can avoid that. (I made this conclusion through extensive experiments... Yet I am not sure about reason...)
Maybe one more reason, I am too dumb to handle your extra script. :)

What extra script?
Anyway, the pipes don't should have a better flow(if game don't have patchfix code inside), the problem is that the pressure is calculated like max flow = stored liquid/2, so bigger is the entity fluidbox, slow is (until not reach an amount of fluid inside), no matter what prototypes u use.
I choise to use storage tank prototypes for add the feature that 2 pipe could be adjacent without get error like "can't mix liquid blabla"

I mean those scripts in your control.lua, like auto-join. Also I realize you have made them into another system (so only connectable with vanilla pipes using the end point intake/outtake, which appears quite complicated for me. I am now using a much simple system, by using the vanilla pipe type and without needing any control.lua scripts.

I found that I can scale up flow rate at whatever I wanted, by adjusting height and base_level inside fluid_box. The flow rate is roughly directly proportional to the height. For example, vanilla pipe has default height = 1. By setting height = 4 as my "pipe +1" new entity, it transferred fluid at roughly 4 times flow rate, measured by circuit. You can look into my code in pipe.lua to see how it is done.
Cannot just modify base_area, or it will have the exact problem as you mentioned.
There are some documentation (with formulas) online that helped me understanding. Links on the main page.

My prime motivation is to get the 1.9 TW nuclear reactor running, by letting enough water flowing, Thus I focus on high flow rate more than everything else. (I have working blueprints on FAQ page, so anyone can easily reproduce. And to study how the flow rate works.)