It's a beautiful kit. The only changes I'd make:
1) engine plate E31 was supposed to have weld seams on the rearmost and side edges.
2) thicken up the armor slabs at the front of the drivers’ hoods using Bondo putty. The M4A4’s hood front faces have distinct bulges created by the casting process with the right bulge being thicker as evidenced by a deeper shadow in all photos. I simply applied a thicker coat of putty on the right hood than the left hood.
3) You can shrink the tail light attachment stalks to more reflect the real thing
4) add a cable lock on the rear engine deck