Welcome to Kelly, K4UPG !
Welcome to our Sierra jewels group.
Kelly just bought a Sierra kit and getting ready to build it. Kelly would love to learn from others and contribute back too. Kelly also looking at possible mods before I get started building.
Well dependign to Your init config I can recommend the KC2 opt., band modules according to Your antennas available and even extreme modules like 136kHz, 500kHz or 50MHz bands. Regarding the mods You can upgrade to 5W out or add some very useful options like SWR indicator, ATU, etc.
Check the Files section for basic mods available. Another mods will come from our member directly for sure.
I am pretty sure that You will be happy with Your new rig as it is Sierra jewel instead of other "only rigs" hi.
73 - Petr, OK1RP