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. 

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