So yeah, it's been a really long time coming, but I finally got myself to share the soundtrack for BK4 and 5 again. Sorry for the really long delay. I don't really browse Newgrounds actively anymore, so pretty much all I get postings here tend to get either ignored or replied way too late.

So anyway, here's the good stuff:
https://dl.dropboxusercontent.com/u/47768980/BK/01_Infiltration.mp3
https://dl.dropboxusercontent.com/u/47768980/BK/02_UrbanSkirmish.mp3/BK/02_UrbanSkirmish.mp3
https://dl.dropboxusercontent.com/u/47768980/BK/03_TechnoNinjaBunnyBeats.mp3
https://dl.dropboxusercontent.com/u/47768980/BK/04_SBFUBAR.mp3
https://dl.dropboxusercontent.com/u/47768980/BK/05%20BerserkAvenger.mp3
https://dl.dropboxusercontent.com/u/47768980/BK/06%20HighOctane.mp3
https://dl.dropboxusercontent.com/u/47768980/BK/07%20Outro.mp3
https://dl.dropboxusercontent.com/u/47768980/BK/08%20Berserk%20Avenger%20(Alternate%20version).mp3

https://dl.dropboxusercontent.com/u/47768980/BK/Bunnykill%204%20Soundtrack%20-%201%20-%20Bombs%2C%20blades%20and%20bunnyninjas%20Part%201.mp3
https://dl.dropboxusercontent.com/u/47768980/BK/Bunnykill%204%20Soundtrack%20-%202%20-%20Bombs%2C%20blades%20and%20bunnyninjas%20Part%202.mp3
https://dl.dropboxusercontent.com/u/47768980/BK/Bunnykill%204%20Soundtrack%20-%203%20-%20Sumo%20Samurai.mp3
https://dl.dropboxusercontent.com/u/47768980/BK/Bunnykill%204%20Soundtrack%20-%204%20-%20Snowball%20vs%20Flint.mp3
https://dl.dropboxusercontent.com/u/47768980/BK/Bunnykill%204%20Soundtrack%20-%205%20-%20Ruby%20Appears.mp3
https://dl.dropboxusercontent.com/u/47768980/BK/Bunnykill%204%20Soundtrack%20-%206%20-%20White%20Avenger.mp3

All of this is released under the non-commercial CC-license, as in feel free to use it in anyway as long as you're not making a profit out of it.