What you need to do is install (but not yet run) the Viper APK:
http://robbiekhan.co.uk/root/files/ViPER4Android_4.x_2322.apk
Then:
1: Install
BusyBox and skip the free version ad window and just hit update without changing any options. This updates the pre-installed BusyBoxto the latest version.
2: Reboot and run Viper4Android and when prompted, install the driver and reboot.
3: Run Viper again and on the 3 dots top right, click the Lock option and set it to headset.
4: On the menu again, scroll down to the UI mode and set it to Expert. The app will need to be closed and restarted after this is done.
5: Once the above is complete, run Viper and on the Headset tab, enable the EQ and apply a preset, or custom one like the screenshot I posted above. These EQ values will vary, you may prefer a different value.
I also scrolled down in the main Headset tab and enabled Clarity and Dynamic and set the gain and Bass Boost to around 10% and 6dB. You can set the clarity option method to Noise+ or Natural depending on the style you prefer and tweak the values as well.
If all goes well, and you've set your music player app to bypass its built in EQ and use external, then in Viper when music is playing, you can click the 3 dots menu, scroll down to Driver Status, and see that the driver is active and next to "Processing" it says Yes. If it says No, then your music player isn't sending the audio to Viper and you need to check the player's settings again.
Bugs:
I noticed that if the head unit wakes up from the sleep mode, then Viper won't auto start at wake. I have set a homescreen gesture to launch Viper if this is the case, just swipe up on the screen and it's up and running in the notifications area.