I've added a grunge/dirt effect to many of the textures. The effect is subtle (but noticeable), so if you're not sure whether or not to download the set, have a look at the attached images. If you do download it, I would recommend keeping the new set in a separate folder, rather than mixing it with the original set. I think the result of mixing the two would be fairly chaotic, especially since I've used the same thumbnail images.
If you do keep them separate, you'll need to copy the relevant .X files from the original set to the new set. The zip file contains a readme file with a list of all the files you need to copy.
One problem with dirty textures on a modular kit is that you can get a very unrealistic tiling effect. To get around this, you can alternate between the different model types (wall, wall ceiling, floor wall etc). This won't work with wall 3 and ceiling 3 (because they don't have the same variety of models), so I've done 3 slightly different grunge patterns for each model (a, b and c).
https://www.dropbox.com/s/lngni2pphhgmudy/Modernscifi%20construction%20kit%20grunge.zip?dl=0
