Congrats and welcome. I'm not on here often (although hopefully that will change soon). Odds are you may know some of this already by now. First...Is your EX RWD or AWD? That will make a difference. Things are a lot easier if you have the RWD. You can use a catback system from the G37 (RWD to RWD). HOWEVER, please know that the midpipe will have to be altered. As for as test pipes, if you have an AWD, clearance may be tricky. I believe Fast Intentions has them for AWD G's, which will essentially work with AWD Ex35's. If you have an AWD, Motordyne ART pipes WILL NOT work without modification (that's what I've been told).
One thing to consider (and I can't remember for the life of me if they're the same) are the flanges. G37's, whether AWD or RWD, have a VQ37VHR motor as opposed to our smaller VQ35HR. Changes like these often cause manufacturers to make small tweeks in other areas. The flange from the test pipe to the Y pipe should be fine, but you need to check the flange at the header. Better to check and verify that first then to start pulling parts and realize you can't use the pipes.
Sway bars...RWD and AWD rears are the same so if you wanted to upgrade those, that's easy. If you have an AWD, you cannot use front sways designed for a RWD G.
BC coils are okay, but most people with them have complained about clunking noises, no matter how accurate the install and initial fitment. Seems to be a flaw in their craftsmanship. Look in Fortune Auto if your budget allows. If you have a RWD, you have even more options. Please be mindful of spring rates.