Dart/Demon/Duster Exhaust Tips - help!

Ok, I'm hopeful this will catch the eye of one of those old timer Mopar experts...
Question: "Can you tell me exactly WHY these have such an odd shape?"

Is it to magnify the sound or deepen it or increase flow or just because that's the way it is...?

I'm considering putting these on my Duster, buuuut they're not cheap and I don't NEED them anyway, but dang they're cool just the same.

I'll check back in a few days to see if this had any informative bites. :cheers:

Thanks guys, I appreciate whatever you can share.