Jfif injection to PS3 Save Data

[JohnCena7877]

 

Hi Guys there's a game on PS3 I'm trying to understand how to inject jfif files that exceed the original size. I am already able to replace existing jfif files by simply making them the same length (if smaller zero the file out till it reaches the same length as the original) its a similar process to this YT video.

https://www.youtube.com/watch?v=lZQKq52dyMA

 

However I'm looking to exceed the original jfif file size, is there any particular way I need to do this? Is it likely to involve having to recalculate some type of checksum or perhaps there's an offset in SYS-DATA file I'm referring to that indicates where a jfif starts and ends maybe. 

[JohnCena7877]

I'm not at home rn otherwise I'd attach the save in question, at the minute I'm more looking for advice on perhaps potential suggestions on how the structure could work