If you are asking if reducers are needed then you are using the stock pipe. If that is the case, the muffler will not simply slip in since the inlet pipe spacing is not the same as the outlet pipe spacing.
A piping diagram of the hemi, https://www.google.com/search?q=2014...8i4_F3Bgn6M%3A
shows the flow looks the same so that is ok.
No way will it bolt in. You'll need to get four 2.5" muffler flanges, four 2.5" gaskets and eight, grade 8, black oxide nuts & bolts for the stock pipe to mate with the exhaust. Plus some extra pipe to deal with the different spacing between the inlet and outlet pipes. All info I've been able to gleen is the stock pipe size is 2.25". A pipe expander will easily enlarge for your to weld on the flanges. Or, weld a 2" long piece of 2.5" pipe o'er the 2.25".
IMO, this is an expensive exercise with no performance payoff with the exception of uniqueness of controlling exhaust sound. That's prolly the reason no one has done it yet. An alternative would be to ditch the OEM suitcase and replace it with a Dynomax X-pipe
54777 for $114. Hope this helps.