Resonators after the manifolds/headers to kill drone/harsh tones, and adding an X pipe will also smooth out the tone and make it less harsh in the cab. Vibrant makes really good resonators.
There are a few different "kinds" of sound to deal with in a vehicle and peel and sticky Dynomat type deadener only deals with one kind. Unfortunately the aftermarket pushes it so hard that the other ways are pretty much totally ignored. Sounddeadenershowdown used to be an excellent source of info and products to deal with the full spectrum of noise reduction, they're closed now but you can still access the info on their old site here-
https://web.archive.org/web/20210609...rshowdown.com/