Jeg's exhaust system: "deep tone" vs. regular mufflers

I am considering the Jegs 2-1/2" kit on my Duster. Running mild build 318, stock heads, ported with 1.88/1.6 valves installed. Running 340 manifolds.

I'd like opinions on two things.

1. Is there a source for pre-made down pipes from manifolds to the rest of the system?

2. What's the craze about H pipes?
I ran 2 1-7/8 pipes out of the manifolds on my high school 69 Barracuda 318 with thrush hush and I loved it.

Can anyone fill me in and get me up to speed?

Thanks!
I'm the original poster. I just used my original headpipes from the old exhaust and welded a flange onto them to attach to the Jeg's system.
My blog has some pics and video for sound:
New Exhaust System Install