I havent had any cooling problems on my nx when turbo, but i didnt have a front mount until now. I was running a water to air intercooler with a stock nx radiator, no ac, slim fans, a nismo radiator cap, and thermostat, and 50/50 water/coolant with 1 bottle of water wetter. I have roadraced on hot days and auto crossed on hot days with no problems. I didnt have much blocking flow to the radiator besides a trans cooler for a heat exchanger, and a ps cooler.
I think for people with large bar and plate intercoolers in an nx a nismo thermostat and an upgraded radiator should definately be considered.
The mishimoto stuff seems to work pretty well, i know a few 240sx guys that have been running them for a while with no overheating issues.