It looks like from the person swapping a 392 into his 2012 that recent Durango SRT might just use a log type manifold just like the 5.7L does.
You need to also swap out the down pipes as the headers are in a different position if I remember...along with the pipe diameter is larger.
Most Chally/Charger owners will either swap out the cat back for the SRT exhaust, or put a reducer to join the their stock exhaust.
Early Jeep SRT's used a similar exhaust manifold to the Chally/Chargers....but it did not flow as well thus the 5hp reduction in HP over the cars.
Maybe a Durango SRT owner here can confirm the design of the exhaust manifolds being used.