FFXUNDUB

Final Fantasy X - HD - Undub Files

Contains: 

Audio (VOICES)
Video (FMV)     
Subtitles (FIXED)

The MetaMenu folder contains the Credits+Audio Bonus video, It's 500 MB, If you aren't interested, save the space and delete it!

First follow this guide to know how to install HENkaku :: https://github.com/s1cp/VitaGuide/wiki
Two steps that are important: Installing Henkaku / Copying back

Once you've read that, It's as easy as drag and drop.

Download this folder: https://mega.nz/#F!h0tVVIbB
Key: !8nsCQ_7xql0XC-JBtVcKcQ

Run MolecularShell
Start FTP (press select) and connect to your Vita from your PC (use FileZilla)
Create a new folder in the ux0: location and name it Patch
Change the name of the downloaded folder to your version: EU = PCSB00395 and US = PCSE00408
Transfer the renamed folder to ux0:/patch

That's done, now to edit the file that will make your Vita think you have an update for Final Fantasy X - HD

Find the sce_sys folder of your game, you can find this under ux0:/app/TITLEID
Transfer this folder to your PC and open it up, you should find a file called param.sfo
Open the param.sfo file using the following program: https://sites.google.com/site/theleecherman/sfoeditor
Change the APP_VER parameter of your game file and put something higher, like 1.01 and be sure to save!

Copy this folder into the TITLEID folder under ux0:/Patch 
File structure should now look like this:

ux0:/Patch
      >TITLEID
              >sce_sys
              >FFX_Data
              >MetaMenu (optional)
              >Version_config

Restart the Vita and play Final Fantasy X - HD as it was meant to be played.

Enjoy! 

- Omnium

Thanks to: 

Mr. Gas and Major Tom for the dumping/mod process.
The Henkaku devs for providing a new way to run homebrew.
S1CP for writing the guide for Persona 4 which helped me a lot with this.