Flash modem topic

I am on CM12.. Lollipop 5.0.1.. And I love it.. But my signal sucks.. I am on NB4.. Can I flash or use Odin to upgrade to NF9 or even NK3?
If I yes, can you please post a link.. I have search all over Google and YouTube.. I just find ROMs but not modems for T-Mobile..

Thanks in advance