[ONLY FOR MDL BOOTLOADER] How to use 4.3 MK2 Modem and Retain Sound - xda-developers
Personally I'd recommend skipping 4.3 and going right to any number of 4.4.2 aosp or Google edition ROMs. You will need the mk2 modem for Google but not aosp ROMs. Cyanogen just released a snapshot of cm11 I'm running it now. Its stable and im getting better data reception so far from 4.2.2 and I still have the MDL modem, **** knox. Happy flashing.