Welcome to the Board.
As far as customizing your Mustang, can you give a little detail about what you've got done so far? Or are you completely stock?
Recently, there have been several posts concerning quality radiator brands. Just check the first few pages of post topics - I'm sure you will see at least one or two good threads.
I personally have a Griffin radiator. Very nice piece. Cools very well and looks sharp.
Good luck,
E