Android 4.4.2 stock firmware has been pushed out to non-rooted users in the last few weeks and for those of you who have not upgraded via OTA (over-the-air), you might actually be in a better position than those who did.
First, the Android 4.4.2 stock firmware update brings you an updated 4.4.2 bootloader, which may not allow you to downgrade to Jelly Bean custom ROMs.
That being said, you can still enjoy the best and latest Android 4.4.2 KitKat official firmware thanks to XDA user Fenny, who has crafted a CWM-flashable version you can use along with root.
This stock ROM with root will give you basically everything same as doing the OTA update and you get root so you don’t have to unroot.
I also found that this ROM can be installed on other S4 variants like GT-i9505, Canadian, or AT&T S4. (If you want to use T-Mobile SIM on another S4 with Wifi-Calling, you could use this stock ROM.)
So, knock yourself out, just make a backup ROM of your current ROM, try out the new KitKat stock firmware. If you don’t like it, just restore your old ROM.
Download Android 4.4.2 Stock ROM with Root for T-Mobile Galaxy S4 SGH-M919 (also can be installed on GT-i9505, AT&T S4, and Canadian) – Mirror @DownloadAndroidRom.com
What is a Custom ROM?
A custom ROM is a custom, modified operating system that you can install on your Android device. Basically it's like installing Windows OS on a Macbook. By installing a custom ROM, you can bypass stock factory settings like locked hotspot tether, install new Android versions early, or even convert your phone into another OS.
With a custom ROM, you can really maximize the capabilities of your smartphone by adding custom features that have been developed by open source developers.
How to Install Custom ROMs
First, you will need to root your device, if it is not rooted yet, follow our root tutorial and root your phone.
Once rooted, you should have TWRP installed on your phone. Installation of a custom ROM is easy if you learn the basic of it. If you don't know how to install custom ROMs using TWRP recovery, see our tutorial on How to Install Custom ROM using TWRP!