Here's a free pack of some killer 808's for Xfer Serum and WAV files. All made from scratch and will murder anyone's subwoofers! Great for any genre that needs that bottom end.. TOTALLY FREE!
make sure you copy the serum presets to this directory (on windows)
example: C:DocumentsXferSerum PresetsPresets
download it here
http://www.traptendo.net/sound-kits