I could be mistaken about this, but I believe the AWD versions of the Magnum and 300C are slower than their RWD versions.
Thanks RLSH700, I tried to find a reference for this that would give a good comparison on the Magnum RWD vs. AWD, but all I could find were some timeslips on dragtimes.com that showed the AWD being a couple 10ths faster through the 60ft, and staying ahead through the quarter mile. The 60 foot time for the AWD R/T was similar to the RWD SRT-8.
http://www.dragtimes.com/Dodge-Magnu...slip-7110.html
http://www.dragtimes.com/Dodge-Magnu...slip-6425.html
http://www.dragtimes.com/Dodge-Magnu...slip-6947.html
Far from scientific, but not much worse than comparing a couple different magazine tests...
The weight definitely makes a difference, which is why with the 6 speed manual in the Challenger, I wouldn't be surprised if it could match/beat the GC SRT-8. I think comparing the Challenger will be close enough to the GT 500 that it'll be pretty close to a driver's race.