Spiral Flow VS Glasspack?

Anyone have experience with these trick-daddy Moroso mufflers? Any comparison between these and burned out glass packs?



Below is a rundown of my setup from someone else's thread where, unfortunately, I couldn't find any help. I believe I have the pertinent info there for any exhaust gurus. Any comparisons of noise, performance, backpressure will be helpful. I have scoured the interweb and only found some opinions from turbo import guys running them in conjunction with a resonator or muffler.

I finally got done building the fire-breathing small block I have been jonesing for since highschool. Very well breathing .40 over 350 with 1.60 exhaust valves and 292 duration cam that pulls to around 6800 if I have the balls to hold it there. (Those are the critical exhaust noise numbers right?)

In playing with different headers and some donated and scrap pipes at the strip, I found that this thing needs 3 inches and a fairly non-restrictive and short system. I understand that this is more of a race setup but here's what I have so far:

Hustler full length primaries to 3 in.
10in centered flex pipes (sick of loose header bolts and this motor TORQUES over) also want to keep the pricey ceramic coated headers in one piece!
3 inch X pipe with 45-deg in and out. Side exit.

I know a 3 inch side exit system is going to growl at me and I'm fine with that. My last and hard decision is between a glasspack or a new moroso spiral deally-o.

 

first i didn't use it but;
if gasses escape faster, also more heat escapes from combustion chamber. and it makes chamber little colder than regular operate of your engine. to operate an engine with zero backpressure is inefficient...

 

Thanks UN,
Definitely not an exhaust guru, but I have read threads disputing the need for some backpressure. I did do some toying around at the track though. Started with the 2 1/2 full system, glasspacks and big bends over the rear axle all the way down to open headers. The car ran best with open headers and approx 20in straight 3in diam. pipes after the collectors. So I'm trying to stay with big flow but decrease the sound for the street.

Anybody? Nobody has tried these things?

 

the moroso's flo through the core and through the outer case which should be about 1/3 more flow than a glasspack
but the good glasspacks with a louvered core I would imagine would have more sound controll . if you have no louveres showing in core it will be LOUD
for more [quieter] sound a longer case muffler is best and also a larger diameter case holds more packing
I have been in exhaust for about 17 years and have all the machinery to mfg. glaspacks and muffler cores

 

Thanks Vik.
Moroso seems to be pushing the fact that the movement in the chamber is what smooths out the sound, and quiets 5-7db from open headers. I don't know what that means to the ear though. Any idea of what a louvered 12in el-cheapo glasspack does db wise?

I'm used to the growl of burned out glasspacks, but my hope is that someone would tell me that these things will take about the same volume out but clean it up a little more than a glasspack.

I guess I might have to be the guinea pig. Worst case scenario, I'll send them to Jeff... if I could just figure out where the fark Palookaville is!