The Challenger hood not opening to the full front edge is a styling or structural integrity issue for the grill. It would be possible to do so current day as in the 05 -09 Mustang (and again on the 2010 model) whose leading hood edge is at the very front of the car.

As for the automatic exhaust, it is identical to the Charger and Chrysler 300 exhaust (ok, maybe a tad shorter somewhere). The manula got a slightly different set-up. Not sure if it was to give a benefit to the manual trans cars in a free-er flowing exhaust or if it is a benefit possible by the difference in transmission girth or positioning between the auto and the manual.