Default [Q] super noob question here

I wanted to flash this rom
http://forum.xda-developers.com/show....php?t=2725750
However it says "Do not mix and match 4.3 firmware (bootloaders/modem) with the new NE4 ones. You will hard brick" I jsut did the 4.4 ota update will I be ok if I flash this? also what exactly does it mean do not mix? sorry for the noob question and thank you for anyone who answers.

Also Im rooted and installed Twrp.