Default How to update AVRCP to 1.4 on stock rooted 4.4.3?

I have a stock rooted (4.4.3) Nexus 5 and a brand new 2014 Mazda 3 with the bluetooth and nav. I want to be able to browse my music playlists, and artist, etc. from the nav like I can with an iPhone. I also want to be able to view my texts, and emails like I can with an HTC One M8. However, the music over bluetooth with the N5 only allows for skipping through every song in whatever order they are in my music player on the N5. The text messages and emails also never load. I get a notification that I got them, but cant view them like I can with the HTC. There obviously is some incompatibility here. Any ideas?

--- Update---
Turns out the issue is 4.4.3 is not running AVRCP 1.4 which is required for root music folder exploring and viewing texts, etc. Anyone try and update to 1.4 on stock rooted 4.4.3?