GMMG has some too:
http://www.gmmginc.net/Exhaust/index.php

 

I am currently running dual exhaust with (2) Magnaflow round resonators (3" ID 4" OD), into (2) flowmasters (3 chambered) all using 3" mandrel elbows and straight pipe TIG welded together and then totally Ceramic coated, and boy its super loud....but I am making 623 HP @ the wheels so I guess its gonna be loud.

Also if you mount your resonators backward (louvered open ends toward the back) it will flow much better at the cost of a little more volume.

 

Do those resonators have any kind of packing? Do they resemble "glasspacks"?
Because the correct way to install glasspacks is so that the exhaust flows over the louvers, not into them (louvers open toward the back).
Flow into them, and they will burn out and/or pack up in no time.

 

I had a set of cherry bombs class pack on this car but the packing would not last. Motor was blowing it out after a fews runs



I had 65 impala ss 327 30 over motor with chamber exhaust install I bought from chevy parts department in 1978 they only had 3 pairs lift at the time because they stop making them. There's a few shop the makes them, But only 1 shop that's very close to the same one's that chevy use to sale that where I bought minds from. I check the Internet to see if anyone els my have used them and how they like them from chambered exhaust sticks all was happy.

I went with 2"1/4 because my cam starts to make power at 3200 rpm to make a little back pressure to help lower rpm for street driving.

That's the 1st time I every seen exhaust set up like your sweet.

 

The Magnaflows I have are Perforated, not louvered, and one of the glasspack style mufflers I have seen actually said to install it with the open ends of the louvers toward the flow, which would seem like it would blow out in very little time like you said.

I will take a pic of the pre mufflers (magnaflows) later today or tomorrow so you guys can see it, not that it really matters, but what the heck.



BTW I like the Chevazda....haha, bet it really hauls in that little chassis..

 

Perforated is probably better and less restrictive than louvers anyway. A couple years ago I replaced a cat with a glasspack (it was a little too raspy without something). It's been a while since the last time I used them, so I made a point of looking at the instructions, and it did say to have the exhaust flow over the louvers. Why brands are different, I dunno. Common sense might make you think to have it blow into the louvers to catch the sound, but it does quiet down the level blowing over and not into.