has anyone installed transcooler on 04 gto?

Hey guys please help. I am Installing B & M transcooler 24000 GVW on my 04 GTO. Can anyone tell me which line i use to hook up to transcooler ? The upper line or lower line from transmission that connects to the back of the radiator. The instruction says upper is usually the inlet line from transmission to the radiator but when I wrap my hand around the upper transcooler line & lower cooler line both lines feels to be same temperature. Which line do i hook up to b& m transcooler, upper line or lower line ?