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Edelbrock use to make their RPM series mufflers. Had something called a 'tru flow' core. I know they made them in at least 3.5"... as a buddy bought some. Fairly large case, and probably what you would want... but, I think they went out of production 10-12 years ago. Borla might be your best bet, if they make one long/large enough to absorb a decent amount of sound. Either this, or if you have room... start looking into 4" diesel stuff. It's a very popular size in those trucks. Good chance of finding what you are looking for.
The DIESEL comment was well down in my post, but that is likely your best bet for a semi-quiet 4" muffler. 4" is a very popular size with the diesel crowd. Should be some decent mufflers available. Just double check their dimensions.

Good Luck
 

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Weren't the borla xr1 tried on a fast door car or something like that. Thought I Saw a video of them testing the weekend before a big race where sound restrictions were discussed. If its them supposedly they did well.
 

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Fundamentally, a diesel muffler works on different inputs than an automotive muffler.
A diesel runs at 1500-1800RPM down the road where a V-8 gasser runs higher RPM.
The noise frequency a diesel muffler is around 75-90Hz for a straight 6 diesel where a V-8 gasser is around 133Hz at 2000RPM.
You can certainly bolt one or two diesel mufflers on and it will attenuate some frequencies, just not the best job for the ones that a V8 makes at most driving conditions.
Donaldson does make good quality diesel mufflers...
 

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Discussion Starter #27
Fundamentally, a diesel muffler works on different inputs than an automotive muffler.
A diesel runs at 1500-1800RPM down the road where a V-8 gasser runs higher RPM.
The noise frequency a diesel muffler is around 75-90Hz for a straight 6 diesel where a V-8 gasser is around 133Hz at 2000RPM.
You can certainly bolt one or two diesel mufflers on and it will attenuate some frequencies, just not the best job for the ones that a V8 makes at most driving conditions.
Donaldson does make good quality diesel mufflers...

This is where I wanted to go with the dB differences behind Donaldson models- maybe a quality muffler, but not designed for my application.

http://garage.grumpysperformance.com/index.php?threads/quieter-4-in-muffler.15782/#post-94525

Maybe it time to test some augers.
 

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This is where I wanted to go with the dB differences behind Donaldson models- maybe a quality muffler, but not designed for my application.

http://garage.grumpysperformance.com/index.php?threads/quieter-4-in-muffler.15782/#post-94525

Maybe it time to test some augers.
Augers are HORRIBLE. They absolutely destroy flow. I'd try a diesel muffler first. At least those are made to flow a LOT of air! As you know, diesels have no throttle butterfly. They run WIDE OPEN all the time, and only use fuel for the throttle. It's why diesel exhausts are so big. They run wide open WITH a big turbo blowing through them... and it all goes through a single exhaust pipe.

A 4" diesel muffler will flow a LOT better than a damn auger. Plus, the auger doesn't do hardly shit for muffling. It's just a baffle that clogs up the exhaust... and muffles that way.
 

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Discussion Starter #30
OK, I misunderstood the dB thing, as I read through the Donaldson muffler spec- it means the amount of engine exhaust noise that is reduced- I was thinking a tuning thing, So with the minimum cfm passed being 1543- it looks like any of the 4 inch inline mufflers would work. Will have to look at pricing vs cfm as some of these are quite $$.
 

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I've have both the 4000 shootouts and the 3000 xlp ....haven't run the 3000s at the strip I use them for street driving but they don't seem to take any more power away...
 

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Edelbrock use to make their RPM series mufflers. Had something called a 'tru flow' core. I know they made them in at least 3.5"... as a buddy bought some. Fairly large case, and probably what you would want... but, I think they went out of production 10-12 years ago. Borla might be your best bet, if they make one long/large enough to absorb a decent amount of sound. Either this, or if you have room... start looking into 4" diesel stuff. It's a very popular size in those trucks. Good chance of finding what you are looking for.

TRUTH!
I run a pair of the Eddy RPMs as resontors behind two short single chamber 3.5's. Great sound, hardly any back pressure.
 

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Discussion Starter #39
I have a pair of Eddy TES headers- pretty good for the money SS. I will be going Donaldson huge case muffler- M090544 perhaps.
 
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