gryfox23 -
Welcome aboard !!! Seeing as how you're new to this VTX board, you may want to help us all (and yourself) out by including at least the nearest large town/city closest to you in your profile area and the year and model of your VTX in your signature line. You'll notice that most folks have some additional info posted in their Profile and Signature areas.
That way you won't have to repeat typing that info in each time you post a question or in response to another member's inquiry for those details should you forget to include the info in your original post.
As you have seen, this info may help the rest of us to provide you with a quicker diagnosis for any problems or technical responses to questions that you may run into with your bike
There is a multitude of "upgrades" that you can perform to your '06 C-model. It all depends on exactly what has been done to the bike so far. I'd say safety items first (steering neck bearings and tires), handling (suspension upgrades - Progressive fork springs and shocks) next, running and performance (PAIR valve removal and valve adjustment, SCAR mod, air box mods, exhaust mods). The loudest exhaust to install on the VTX1300 is the Hard-Chrome Sideburners a 2-into-1 system with a 4" outlet - YIKES !!!
Then you can start playing with the functional, cosmetic or "appearance" items - lights, mirrors, saddlebags, windshield/fairing, L.P. and turnsignal relocation, etc...
Too many options to list. However, those I have listed in the order of priorities - safety, handling, performance and cosmetic - should be the way that anyone approaches a bike customizing routine. Unfortunately, it usually happens in the reverse order from what I have suggested.