There is a lot of clutch chatter at idle and low RPM in the XX. I got rid of it for about 800 miles by using Loctite retaining compound on the PTO to crankshaft splines, but it came back. I installed the Speedwerx PTO shaft (with Loctite) at that point. Still quiet, but only 300 more miles.
The 4 springs that hold the muffler tight to the header pipe will resonate - run a line or two of high temp RTV the length of the coils.
Oh, and do a search. This has been covered a few times.
New to wild cat forum I have a 2018xx limited a lot of noise by insulating the console and rapping the headers also insulating the top lid of the air intake for the clutch and a rear window
Hope this helps