There are two options: upgrade all the textures with the utility or use ingame filters to upgrade textures on the go. Since the latter is much more performance heavy, I personally prefer the use of utility.
Here are a few examples of upgraded textures, using XBR 4x Method:
Spoiler!
https://code.google.com/archive/p/2dima ... /downloads
If you like the results, I might take some of my personal time and do an upgrade for all vanilla textures. Some need slight editing, though, but overall it is an easy task IMO. Just time consuming.