[Sprint LG G2] :
Before event thinking about anything, please create a backup of existing ROM. ;)

Why the post?

CM13 is BUMP compatible. ( BUMP explained below)

The Sprint G2 is having very confusing Bootloader and Bootstacks combination needs for every major release of Cyanogenmod.

e.g.

Initially we had to have ZV8 modem for CM11 without it we had bootloops

We were confused with LP-loki and LP-BUMP bootstacks before using CM12.1

I got bootlooped twice doing the upgrade, so I thought to share the experience to save you from such touble and make step-to-step guide for you to help to jump to the amazing Android 6 :angel:

What we need -

Bump TWRP Recovery - http://xdaforums.com/lg-g2/development/twrp-twrp-2-8-0-0-kernel-f2fs-tools-t2898705 (Thank to blastagator :) )

Hybrid Bootstack - http://xdaforums.com/lg-g2/development/boot-g2-hybrid-bootstacks-t3183219 (Thank to daniel.stuart14 :) )

CM13 based roms (few recommended below)

Resurrection - http://xdaforums.com/lg-g2/development/rom-ressurrection-remix-m-t3271114/post64315465#post64315465 ( Thank to varund7726 :))

crDroid - http://xdaforums.com/lg-g2/development/rom-crdroid-t3120790 (Thank to firebird11 :) )

waiting for Bliss 6.0 from Team Bliss :o

Gapps for 6.X.X ( http://download.dirtyunicorns.com/files/gapps/banks_gapps/ )

Why to update TWRP?

CM13 is BUMP. If you are like me and used FreeGee to downgrade aboot, for installing TWRP, then you are on JB bootloader which is Loki based.

Loki is synonyms to JB bootloader & BUMP is synonyms to Kitkat Bootloader.

So if you flash this ROM with current setup, you wont be able to go beyond Bootscreen LG logo (in other words, you would softbrick) because of Modem mismatch.

And if you flash the Hybrid bootloader after flashing ROM, then logically you should be fixing the above problem but your TWRP, which can be booted on Loki (JB), wont be able to boot behind Kitkat Bootloader. :(

So we will make the TWRP capable to boot on Kitkat bootloader and then start to play with the ROMs.

So first, Install TWRP-thermal from above link. I would recommend to update your current TWRP to 2.8.6.0 with official TWRP files (https://dl.twrp.me/g2spr/) and then flash the above zip to upgrade to 2.8.7.3

Which Bootstack and what about bootloader?

The BUMP recovery can boot against JB bootloader and Kitkat bootloader. So what you have now can boot on current bootloader. So basically you can restart the recovery with JB bootloader without any problem. Reboot and flash the Hybrid bootstack from above link which takes care of everything.

Remember to reboot into recovery after you flash the bootstack.

Now for ROM installation the usual procedure is needed,

Wipe Dalvik, system, data and cache

Install ROM

Install Gapps

Reboot

Few common problems and solutions,

Bootstack failing signature validation - (Checksum of the bootstack-ls980-CAF-signed.zip is : e32c3c4d5ece4749903ef7502485f488 ). So if this is matching, uncheck Zip signature verification and flash.

Google Now-On-Tap not working - This will happen if you have opted for Nano Gapps file which would not have all apps for Now-On-Tap (Just Google app is not enough probably ).

So happy flashing and hit the thanks if you see above information useful.

Let me know if you want any clarification regarding above process or any specific points.