"Gmod99" said ...If you're using XNALara (or XPS) .tga files don't need an add-on. I don't know what you want to do with the files, but you can edit tga textures in any image editor, like photoshop. Opening them in 3ds Max wouldn't be a problem either. If you're trying to use them with GMod, can't help you there. Don't use the program.
Can Someone Tell Me How You Install Addons That Uses TGA Files ?