Customizing menus?

I've been thinking about customizing all the retropie theme, I say, making a new pixel theme and creating by my own new musics for the menu, listening some of the playlist incorporated sometimes is boring, I've deleted one and another music already. (8-bit music is great, I love it. But menu music?) The theme for the emulationstation is the worst part, I guess. I'll make completely free to use all this stuff.