There is already another thread in this section with a lot of information on issues with Viper here: http://forum.xda-developers.com/show....php?t=2543796
I have attached a zip I made that will automatically install the app in priv-app and set permissions. I have no issues with any usage of Viper on SlimKat ROM. All options work for me on Google Music, Tune In Radio, Youtube and works over wired headphones, bluetooth, and speakerphone. Personally anyone that has already tried installing this and had any issues I would uninstall every aspect of Viper on your phone(both drivers and apk), dirty flash the ROM you're on, then flash the zip, boot up, install drivers, then reboot. If that doesn't help and you're hell bent on trying to get Viper to work I would make a nand, clean install you're ROM, and flash the zip to see if it works as it seems some ROM's have issues with Viper. If it doesn't work just restore the nand.
P.S. also keep in mind that with the apk installed in priv-app you will need to flash the zip at every ROM update and reinstall drivers then reboot on your first boot. You won't lose your settings though unless you wipe data.