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.
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"
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"
Fairchild's Decompression Toolkit
My Hex Tutorial