If you really want to be picky with a CAI, I would choose the JLT for sure, but to be completely honest, all CAI's are going to give you roughly the same gains, and therefore I would choose the cheapest one I could find. I would buy the $84 one off of American Muscle and save myself $150 to put towards the UDP's. As far as UDP's, there is no other way to go than Steeda's.
2001 V8 4.6L Mustang GT (auto) - daily driver
2004 V6 3.9L Mustang (auto) - sold
God bless all!