I get home from work the other day and my wife tells me I might want to look at the truck as it's "a little louder"

Sure enough, tailpipe rusted right in front of the muffler and completly separated. I got busy and ripped all the exhaust from the muffler back, out of there.

I now all I have is what's left of the stock exhaust dumping out just behind the cab.

It might just be coincidence but it seems my fuel economy went up at the same time as the exhaust volume. Could be that my wife has been a little (lot) lighter on the throttle to keep the noise down...

anyway, I need to do something about the ghetto straightpipe and need exhaust alternatives.

Suggestions?

I'm also looking at installing a pacbrake exhaust brake. How will that affect the volume with or without a muffler? (I'm split on sticking a muffler back in at least until I figure out what's with this fuel economy...)

 

Mine has a 4" system with just a cat on it - no muffler - and a 5" chrome tip about 18" long coming out behind the right rear tires. At least I think it's a cat instead of a muffler. It's a little loud, but I love the sound. I suppose the cat quiets it a little. I don't think yours even requires a cat for emissions. Bought mine like that, so I don't know what effect it has on mileage.

 

No, there's no cat on mine or resonator...

Simple straight pipe right up to the turbo. I suppose I could get a filler piece to replace the muffler. That'll move the sound a little farther back.



Anyone else notice a difference in MPG with a straight pipe vs. a muffled engine?

 

I noticed a little better MPG when I put the 5" exhaust on, the muffler is a straight through type. I have heard that the cat doesn't make a lot of sound difference.

 

The pacbrake won't quiet the engine one bit, and when you turn it on it sounds like an air compressor gettin ready to explode. Mine is straight all the way from the turbo (pacbrake) back. It's loud, and even louder when you flip the brake switch and it engages

 

I had my cat off for some repair work. BIG difference in sound.

I don't have a muffler and the cat kills just enough of the Cackle or RAAAPPPP noise. I called it --hole loud. Because that's what people would say, "What an --hole!" If you're really worried about it, knock a few 1/2" holes through the cat elements. It's a flow through design and offers very little resistance at normal rpms. A couple speed holes might make for some piece of mind.

Now it sounds good with a little whistle, nice and throaty without the drone.

 

I have read on this and other forums that the stock or lightly modified 5.9L Cummins (such as a programmer) gets maximum benefit from a 4" system, and no added benefit from a 5" or larger over a 4" system, unless it has some mods, such as a significantly larger turbo. Never tried it myself. Just FYI.

 

A diesel needs to breath, that's why your MPG's go up when you take your CAT and Muffler off. Although the first couple of weeks, after removal, your MPG's will go down because it just sounds so good its hard to back out of the throttle. Once you start driving it normal your MPG's will definately go up at least 1 or 2.

 

You could tell the turbo spooled faster and a slight MPG gain but the biggest difference for my truck now is the sound. My truck sounds freaking great at idle or WFO! I love the sound of the 5" Magnaflow and it supports any mods I do in the future.

 

If you don't want the noise, Donaldson makes a quiet muffler that is around 100.00 to 150.00 with very little restriction.

 

Ha ha! No, I wouldn't have thought the pacbrake would quiet things up any, but the visualisation of people diving for cover when I come to a stop made me laugh....