From your experience/older threads..Is the Dyna mostly preferred for the ease of attachment/bracketry or more than that (e.g. performance, note, aesthetics,pipe diameter...) I seem to recall its the former (ease of attachment) but I may have forgotten something more important......Look for Dyna mufflers from models without the crossover pipe. I don't remember which years. You can use the later ones, but you'll need to weld plugs into the crossover ports.
Are the cat converters in the muffler themselves or in the crossover section?Here's another vote for the earlier Sportster mufflers. While I cannot speak to CX500 fitment, I put them on my GL1000. They sound great at idle, have easily utilized mounting tabs, superior chrome and lack the crossover. (The crossover can be plugged, but those without it are "cleaner" looking).
Also, be careful not to get a pair with the catalytic converters. They'll work, but are heavy and quieter.
One more thing, the Sportster mufflers are designed for a roughly 1000cc engine. They match well with the 1000 Goldwing. I'm not sure what their tone would be with a 500. Here's my 1000:
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