TTi step vs. 340 manifolds

So I don’t have to start another thread:

What’s wrong with glass packs? When I was a kid it was what eelveryone wanted/had. Then came Flowmaster. I tried those and found I would rather have the glass pack sound. Are they too open?
I love the sound. Being that this car will be my Day 2 car I think they would be more appropriate than a muffler that wasn’t around back in early-mid 70’s.
I just don’t see anyone building exhaust with them anymore.