From personal experience and what I have read so far, MSRP is the best you may do. Mine was 51500 with the nav, uconnect, and polished wheels. The factory is deleting the tonneau and giving a 1k credit - haven't had an explanation why yet from the dealer. My truck is built and in transit. Due in the next 2 weeks.
For the Nav system, they made changes in 05 so it's not the same as the 04. However, it is the same unit (as I understand it) as the one in the '05 Magnum. The link to that is below.
http://www.dodge.com/magnum/interior...ndex&type=left
slbelt
'05 Black QuadCab SRT-10 (in countdown to delivery...)