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Discussion Starter · #1 ·
So, I'm nearing completion of installing the 4bt in my GMC 3500 Crew Cab, and I'm looking for advice for exhaust systems. I'd like to go with a single 4" stack with a turnout from somewhere like dpppower.com, but I'm not sure what to do about a muffler. Anyone running stacks with a muffler to quiet things down? It needs to be wife and children friendly, as we want to be able to ride in the truck for long periods without being drowned by the exhaust. Are the in-stack mufflers any good, or should I look for the underbody ones? I don't have _that_ much room since it needs to stay between the cross members.

Don't get me wrong, I love the whistle and grumble of the 4bt, but after 4-5 hours, it can get old. To keep the interior noise down, I put the asphalt sound deadening mat on the floor, then a layer of jute, then another layer of jute that was attached to the new carpet, and then finally the carpet. BIG difference between that, and the bare floor.

--Mike Jackson
Greenville SC
1993 GMC 3500 Crew - ex 6.5 and 454 (PO) - 4bt, cpl 858, dodge nv4500 with gas input shaft, custom pilot bearing, all autometer ultralite gauges, no pyro or boost gauges yet (soon)
 

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I'm running a Donaldson muffler. it has a 24" body with a 9" diameter. it's supposed to quite 12-15dB.

I'm not sure how well it works to be honest. I have a full bodied SUV too, so it wasn't that bad to begin with. At Idle it sounds about the same. I know on the High Way it isn't annoying at all, but again i have an SUV and the stack isn't right behind my head.
 

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Mike, glad to find someone in my area. Would love to see your setup. Mine will hopefully be done very shortly. I am having it done for me, I am NOT a mechanic. PM me if you would like to meet sometime. Morvin
 

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You can run a muffler but the problem you will still have is the exhaust still dumps out immediately behind your head. The only way to truly make it quiet on long trips is to run a full exhaust that dumps out back where the stock exhaust did.
I have had stacks, straight pipes, and short exhausts that dump in front of the rear tires and by far the quietest is the full system.
 

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Discussion Starter · #5 ·
I'll measure to see what kind of room i have underneath the cabin for a full sized muffler. Thankfully i've got some room there to play with, with the truck being a crew cab and all. I'm still leaning towards a single stack, but if I have to dump it in front of the passenger rear tire, i can handle that too...
 

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Discussion Starter · #7 ·
So I ended up using 3" pipe from the downtube, to a 3" turbo muffler, and a 3" turnout in front of the passenger side wheels. It sounds great, and I can see the exhaust in the rear view... =)
 

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hey dark angel

how many horse power and torque are you expecting from your engine? Will your truck be ready for towing and what kind of towing potential are you expecting?
 

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Discussion Starter · #9 ·
When i dyno'ed it, it put out 105HP, 245ft/lbs of torque with that setup. The only towing it's going to do is maybe a ski boat. Mostly it's a grocery getter and DD'er. It's getting 20 in town, and 24 on the highway. I've got some taller tires to go on it which should help with the milage.
 
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