mine?
not that much. The only things I did were adding a bit blur in the center, adding a radially-blur as overlay and change the colours. But it took some time to try around what looks the best, but if I'd do it again it would take around 3 minutes I guess.
For my latest track
The ingame graphics were only at fast or very fast I can't remember. But it looks al right doesn't it with the help of some small Photoshop tweaks. (I'm a Photoshop noob BTW)