There is a guy name Decaf and he is famous accross all the car audio boards for slowing music but not ruining the song or adding clipping and he has about 30 ZIPS of over 20-30 songs that are just all remade into a little slowed way louder versions that you guys NEED to try out.
http://splcomp.proboards.com/index.cgi?board=tech&action=display&thread=2960&page=1Theres a list of songs in each zip so you can tell which ones are in each zip. I can recommend a few:
Gucci - Atlanta Zoo
La Roux - GOing in for the kill
those are 2 really good ones.