Since Idlehands released his picture depicting what values are where, I thought I'd explain how things work a bit better.
First thing, I've had some people tell me that their saves weren't being modded properly.
This seems to be an issue with Horizon. So I suggest using Modio.
Pre-modding Steps:
Get Modio or Horizon (Modio suggested)
Get Idlehands88's Picture (link below)
Get Fairchild's Decompression Toolkit (link below)
Create folder in "C:\" named "Saves"
Put dd.exe into "C:\Saves"
Modding Steps:
1. Put save on thumbdrive.
2. Put thumbdrive into computer.
3. Extract DunDefSave into C:\Saves using Modio/Horizon
4. Open C:\Saves\DunDefSave with Modio/Horizon
5. Click "File Contents"
6. Right-click DunDefHeroes.dun
7. "Extract File" to C:\Saves
8. Open command prompt window (Windows Key+R then type "cmd" into Run window)
9. Enter "cd C:\Saves" (Now you will be in the C:\Saves folder)
10. To decompress: dd.exe -d DunDefHeroes.dun save.decompressed
11. HEX edit your file. I suggest using Idlehands' tutorial or mine.
12. To compress: dd.exe -c save.decompressed DunDefHeroes.dun
13. Open DunDefSave in Modio/Horizon
14. Click "File Contents"
15. Right-click DunDefHeroes.dun
16. "Replace File" with C:\Saves\DunDefHeroes.dun
17. (Optional) Rehash and resign
HINT: While in cmd, you can use TAB to finish file extensions more quickly. Ex. Typing "save" and hitting TAB will finish it with "save.decompressed"
Links
Idlehands88's Picture
Fairchild's Decompression Toolkit
My Hex Tutorial