Hi, I was looking for a tutorial how to edit the savlib.dat, because I wanted to add games which aren't included in niu's custom savlib.dat. While googling I found one in japanese and the creator of this tutorial didn't just explain how to edit it via hex-editing, he even included a very easy to use tool to do it for you. You just have to tell the game-id and what save size you want it to use and click save. Download ndssavlibedit001.zip and try it. Hope it works for you. I'm going to test my new savlib.dat know. Edit: Seems like deleting entries doesn't work, but adding new entries works fine.