I found in another forum a couple of files which allow us to add MegaBass, one of the most beloved features of Sony Ericsson's W(alkman) phone series. I bundled them in an update.zip to be flashed with Clockwork Mod, and given that they work in all Xperia phones, I've decided to spread them around
I hope it's useful!
MegaBass Installer
MegaBass Uninstaller
*Note* I didn't make these files nor am I savvy enough to discuss their effect. They've been tested in most models with success, though, so again, I distribute them in the hope that they can be useful.