I didn't have the manual with me, but this link has a small section of the differences. http://www.chryslercanada.ca/product...r_HeroCard.pdf
I test drove an unlimited with the stock system, and was ok with the top on... can't see it being that great with the top off. I ended up going with the upgraded system, and it is better than any other "stock" system I've had before (roof on or off). I'm not sure if the 2-door makes a difference, but being a music lover, it was worth the upgrade IMO.