First off, welcome to the forum.

Ok I got an 83 cb550 nighthawk, it's my first bike and I'm ready to do some customizing.
Second, why don't you get to know your bike for a few thousand miles before you go cutting and gutting? Better yet, why don't you get to know how to ride a motorcycle before you do that? I guarantee once you've actually ridden it for a while you'll be less eager to cut a perfectly good exhaust. You'll also find Soichiro Honda's gang made a pretty good, well rounded bike right off the showroom floor.
Does anyone have any suggestions on the best exhaust setup on these bikes? Is it possible to gut the stock pipes for more sound?
The best exhaust you will ever find for a 550 Nighthawk is the stock one. Yes, you can gut and destroy the stock pipes to be obnoxiously loud. Why bother? So you can rejet the now lean fuel/air ratio?
You're learning to ride. There is no need to learn how to tune a fuel/air ratio at the same time, or that hacking away at a bike often has more effects than you ever intended. Focus on why you bought the bike - to ride it.