Muffler opinion

Hello,
when I bought my new to me engine, the guy threw in a couple of mufflers from his pile of parts. They have never been used but I was wondering if anyone had an opinion on this style of muffler. I'm going to go with duel exhaust soon on my 318, but I don't want the car to be obnoxiously loud as several of my neighbors have babies. I'm new to this but I think these are a kind of glass pack? they have 3- inch inlets/outlets off centered but the pipe goes straight through with a bunch of holes in it. There is no brand name on mufflers.

Anyway. Has anyone put this style exhaust on a 318? How did it sound?