Possibly looking for a new exhaust

My '78 KZ650 has been getting a little louder as of late. After a little searching, I found a hole on each of the end of the mufflers. They aren't bad but the bike looks pretty good and don't want a crappy exhaust on it. Can I just find new mufflers somewhere that are the original style? What kind of after market exhaust is good? I am looking to keep the bike quiet since I work til midnight and don't to wake the wife and neighbors.

Weld the hole closed, unless it's a rusted hole.