P.I.E. Interface Vs. USA Spec Interface

[DNY]

I have a 2003 VW Jetta. Wanted to hook up to my existing Monsoon unit through the trunk. Have my choices down to the P.I.E. or USA Spec interfaces. Was wondering if anyone has exepreince with these 2 and what the differences may be. Didn't seem to be much. A concern I had was that there seemed to be a "chip" upgrade necessary for the PIE model and that the USA Spec interface did not come with a cable long enough to be threaded from the left trunk area to the front right glove box.