Safestrap users, see ggow's thread instead.
Using draxie's tool (upHDX), I've created TWRP-friendly ZIPs of the stock firmware that leave the recovery and bootloader intact. Moreover, I've disabled OTA updates as well as lockscreen ads.
I'll try to keep this thread up-to-date should Amazon push any new versions. Feel free to make requests for any previous releases.
Side note: if anyone's ever worked with the AROMA installer, shoot me a PM.
How can I back to totally stock OS? (Means no TWRP recovery)