Well the pressure is not that great, when I worked for Modine, the transcoolers were tested to 125 psi. Never having checked pressure at the cooler ,I would think a racing unit with a 200 psi would be at that 125 mark at the cooler. Remember when running hard lines, you will need some kind of flex line at one of the connection on each line to absorb vibration and flex. Aluminum lines will not take much before cracking. If I were running a hard line it would be stainless. Free is good, but not if it cost you a trans, or even worse a racecar due to failure. Both of my cars are braided steel with an fittings.
Hope this helps,
Dan