Great writeup, this is exactly what I have done this weekend. I have taken away all the OEM hoses which is a big restriction with many bends and turns and instead put in new hoses with less bends and much larger inner diameter. I have testet the flow with and without the supercooler and didn't see any difference in the flowrate. I did whant to read the preassure drop over the supercooler but didn't manage to get any readings from dashdaq. I don't know why, maybe be sensor is failing or the preassure is not high enough to give me a signal.
I'm about to build a second heatexchanger in the front of the supercooler, the same idea that you have. But I need to test the parallell vs the serial connection. Somebody says parallell and other people say that I should go serial.

We could make a group buy of the second heatexchanger if other people are interested?

I think that the CM90 does a great job, my car has been apart since march this year so I can not say how it performance in daily driving bit I think that this pump is the solution for increasing the cooling performance.

/Adam