If you are going to use 120mm fans, then I've found this:
Cooler Master XtraFlo 120 Slim: http://www.coolermaster.com/cooling/xtraflo/xtraflo-120-slim/
It's PWM. 15mm thick. At minimum speed it is simply inaudible, at max speed it will be a bit loud but it will generate thr airflow of 58,4 CFM and static pressure of 1,76 mmH2O - very powerful.
Unfortunately, I still haven't found any good slim 140mm fan.
Hope I helped.