Thats prob it. I knocked it all out at once + installed new speakers + new radio so it was night/day difference.
I don't remember the research 100% because it was 6 years ago but I'm pretty sure the hood and roof are pretty big contributors.
I did neither of them or my fenders.
No mater what anyone does to help reduce noise unless you clog up the pressure regulator in the cab (located in back wall near the bed) noise will always have a clear pathway in & so will dust. The in cab filter is a total joke in the front especially since they leave the rear wide open to suck dust into the cab from.
I think I used a sponge to help keep the dust out + a little noise but mostly dust.