Well, actually this mod does NOT improve graphics, the function of this mod is to prevent the shader missing issue that often happens in rFactor if you have lots of mods installed. With this shader pack, all materials used in the mod will be rendered correctly.
As for tracks, I used Hope racetrack, Iriški Venac, etc, most of them are made by Lemax: http://www.lemaxsimracing.com/rfactor