Overall, this is another way to prove to you that rooting and custom ROMs make your older phone better and just as good as newer phones like the Note 4. So, if you have a model that supports it, give it a go this week(end) and do let me know how much you like it!
Download APBLCP Kernel/Bootloader/Modem package [FOR AT&T Note 3 ONLY]
For AT&T Note 3, installation is same but using SafeStrap (See how to install ROMs using SafeStrap here and use Stock ROM SLOT!!!), then you do need to put the phone in ODIN download mode and install APBLCP package after installing ROM!!! (See latter part of video for step-by-step tutorial!)