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Discussion Starter #1
I bought a used 2004 2500HD with the LB7 engine. I have a couple of questions though...the muffler is kind of loud and I was looking and noticed that there is no cat on it. Did this engine come from the factory like this? Also is there anyway I can quite it down? I'm not concerned with the power gains of the aftermarket muffler, but don't have any idea where to get a factory muffler without going to the stealership. Any ideas??
 

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yea that was the last year duramax didnt have a cat, they actually switched in 04.5 with the lly's. they have a factory muffler in the dieselplace market place for sale i seen, but ur truck should already have a muffler, unless they straight piped it.
 

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I think the Califorina ones had em, where ya from?
 

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Discussion Starter #4
I live in Tennessee
 

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Discussion Starter #5
Can someone post a picture or describe what the factory muffler looks like on a '04 LB7?
 

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I don't have my oem exhaust in town but you should be able to look under almost any duramax to tell what the oem looks like. How big of diameter is the pipe? There are a lot of people like me who have their stock exhaust sitting around because we added a down pipe back exhaust system. Wouldn't make much sense to ship it but could figure something out. I see from your signature that you have an lt but I don't think they had the "lt3" lingo yet.
 

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Speaking about my 02 ~ muffler is oval, the input/output nubs are not inline ~ not straight thru flow. While I've a Banks now, I did remove my CAT for a spell ~ the missus complained so reinstalled it. Now the greenies love me.

Another source for noise could be the front/downpipe joint/connection.
 

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Discussion Starter #8
If the stock pipe is oval then mine must be an aftermarket muffler because it's round.
 

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Discussion Starter #9
The only thing I can see stamped on the muffler is "Made in Canada."
 

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check the pipe size.....if it's 3.5 inch it factory...if it's 4.5 it's aftermarket.
 

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I have a 2004 lb7 no cat 3.5" stock exhaust. Stock pipe is round. Not as loud as a Furd. Started using 2 stroke oil after reading one of the current threads on here. Now it is super quiet. Warmed it up this morning. Smooth running from the get go. When I went back out I heard my neighbors big flatbed gasser two doors down. Could not tell the Dmax was running over his. Went to lunch with the wife yesterday. She was asking what I did to the truck. She liked the new sound;) I'm not looking for sound as much as I am after longevity. This truck has to last me a long time.
 
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