Welcome! The most common 4-1 exhaust system is the MAC which comes in a few variations (all black....black header/chrome pipe, or all chrome)....these can be had from Dennis Kirk, Bike Bandit, etc. You might also find an older used or even a NOS Jardine or Marshall on eBay if you are patient. I'm sure there are others but those are the most common. Of course, you can have something custom made or pay big bucks for a Benji's 4-2....just depends on what you want and how much you want to spend. I had a MAC for a very short time on my bike and just didn't like the sound....but that's just my opinion.
You may already know this, but the frame on the 72 CB500 is basically identical to the 74-76 CB550K (not F).....so if you find something that was specific to that bike....like a factory 4-4 exhaust, it should fit yours as well in the back where the exhaust mounts without any modification.
Show us pics as you progress!!
