Yea, I was going to have a play. I started in Sanctuary with the road (as I thought it would be easy...Post #6) then I couldn't work out why Bump maps made things awful and the textures were so 640x480 looking. (I'll put stuff up in the wiki soon about base Nvidia settings, just distracted with textures atm)
Because of it a know a lot more about bump maps but still hazy on the Specular, But as it turns out I did not know that FO4 runs 3 textures over most of the world.
Base texture, your texture and an overlay or dirt effect (and Fourthly the water effect, the fricken thing sits on your texture and steals your bump for your effect, rendering the overall bump basically transparent to your texture unless your looking into the sun/light source AAARGRGRGRGRGG).....
While doing roads I was able to make them snazzy but then I was playing with the gravel (in the two pics above) I could not get the bump to do anything "Visible" In the upper "dark gravel" is just the specular played with, the lower one the specular is set more neutral so when your facing the sun the "glint/shine" works.
Roads seem to be excluded from this "issue" like some textures have extra maps like height maps _h.dds if you play with that texture you can have fun with height+Bump but only with the 3-4 textures that have been allowed to do it. (i.e. cobble stones) also some _d.dds textures have an alpha channel not for masking like 98% of them but a proper occlusion map.....it's all so randumb.
Sorry been smashing this for 30hrs or more, just rambling about stuff now.....