I didnt use a controller,i just use a manual switch, that way i know if its on or off.You will need at least a 100A alternator.I trimmed my shroud a little to make it a little thinner, but make sure you dont trim too much, thefan could rub the core.
side note: on my way home from vacation in my 06 GT, my car started to overheat.I didnt know the fan stopped working. I pulled over, had some tools from my R/C car, turned out a relay relay melted.Cut some speaker wire from my amp and jumped the relay tp get me home. Point is, i couldnt tell if it was on or off because its controlled by something else.