Pressure in transmission lines?

[2006 Blue TB SS]

Does anyone know the approximate pressure in the two lines that go from the transmission to the built-in cooler in the rad? Is it less than 25PSI?

I'm putting in a tranny cooler and I'd like to run either some hard lines or braided lines between the new cooler. Also, if I get a big enough cooler, is there any reason as to why I should still plumb through the existing built-in cooler?

Thanks for the help.