This will be some testing info I've tested personally over multiple trucks for those looking for that perfect sound. Really has zero effect on power but if you want that great cummins grumble we all know and love then think about this one>>>>

 

so your in the market for an exhaust? There is tons of options and brands....so brand is pretty much irrelevant... only changes really are the outlet angle. MBRP comes back on a 45* outlet, Diamond eye 90* outlet and some others do 60*. Really it doesn't make that big of a difference other then the amount of sound you hear in the cab. Windows down 45* is quietest, 90* is loudest. You'll hear it crack and echo off everything. Windows up 90* is quiet at speed USUALLY, 45* can start to drone at speed due to the low pressure area behind the exhaust pipe/tip. It's not much but it exists. Larger the tip the more drone at high speed.

 

So brand isn't a big deal. Now 4" VS 5", so there isn't a difference in power, we run 4" down pipes on second gens and the flow rate of 4" OD pipe is (3.8" roughly ID) is such a high CFM that it doesn't really matter on a 5.9 liter. Your Peterbuilt 13l CAT engine would like 5". So that said 5" is deeper, tighter fitting and tends to drone more in the cab. Yes it sounds better and I use 5" whenever possible. I love the deep grunt and burp sound, it just screams cummins! Cheap 4" systems will gain you the same power but it's a little more raspy.

 

Now the MOST IMPORTANT part! The material!!!! This makes a huge difference in sound, no performance gains but the sound change is amazing. So alluminized tubing that 80% of us run is honestly crap...in salt conditions it corrodes in a way that turns it a black color over the years. The wall diameter is usually a hair thinner depending on manufacture. The pipe itself TYPICALLY isn't truely round, when it cools the seem in the tubing warps a little So assembly sometimes can be a bear. My personal pet-peeve...drone. Alluminized vibrates, bad...you hear it under the truck, you hear a sound reverberation in the exhaust note and worst of all it vibrates and resonates into the cab from the pipe vibration under the truck. I absolutely hate drone, it's annoying. That said, stainless steel is the best! Even with a thin wall tuning the vibration/reverberation and sound dampening of the stainless is second to none. Yes the tubing is vibrating still since it's connected to the engine and of course everything vibrates but, it flexes less and holds up better to conditions. No corrosion. Some surface rust may show since it's probably from china but it'll last much longer. From personal experience a stainless system also has a much more crisp and clean sound. A to B the drone is near gone in the cab even with 5" straight pipe and a large s300 or 400 turbo that's loud beyond loud. One reason stacked trucks sound the way they do is because the stack is stainless which cleans up the exhaust note. A 4" stainlesss exhaust vs 5" alluminized, the 4" sounds better and cleaner. Much more of the deep burp noise. My personal fav is the 5" stainless though, if you want to make people think you have a small pecker in your wanna be Peterbuilt this is what you use. Deep, crisp sound with little to no drone. Each truck is different, the amount of hangars and style hangar make a big difference as well. Stacks attached to the bed, vibrate the bed and cause droning well same with under carriage exhaust. Make sure your insolators are soft and properly sized. It'll help tremendously.

 

ive personally had 7" stack systems that you couldn't hear in the cab with the windows up, a floating stack system looks a little weird when driving, it moves independent of the body floating on the insolators attached to the frame. But it's very quiet when you want it to be. This also reduces the stress on the pipe, turbo and manifold as the engine twists under load.

 

from personal experience: I've got 2 2nd gens, one with 4" stainless straight pipe and one with 5" alluminized with a diamond eye stainless muffler (came with the truck brand new but I'm going to switch!) if you listen to both trucks in person the 4" stainless sounds much cleaner, crisper and more angry when your on the throttle. The 5" sounds like the echo in a tunnel. Like multiple vehicles are racing due to vibration and reverberation. 

 

Now for some word to the wise info...please for the love of god don't use the stupid crush clamps... they are crap. They bend the alloy pipe so bad it hardly ever comes apart without a torch. If you want to swap turbos or mufflers or whatever don't use crush clamps. I've had so many that are so bad I just cut pipe, butt it together and either band clamp it or weld it. It really sucks to do guys... if your gonna run stainless, good stainless  pipe doesn't like to bend, so the crush clamps will actually bow and not compress the pipe but rather itself. it tends not to hold and a few miles later you got yourself an axle dump you didn't want it even an open down pipe and the muffler is in the grill of a Prius....don't use them. SO that said, the best, easiest and most adjustable/usable way is the overlap-band clamp. Slide your pipe seconds together, overlap the band clamp and get it really nice and tight. Some will have a pin hole leak right around the bolt location, if that's a problem you can use some paste on the pipes swelled overlap to help seal it for inspections and such. Now you can switch down pipes, mufflers, axle dumps etc without getting the hammer out. Just unbolt and slide apart! Stainless once again is the easiest for this and less opertunitly to leak. DO NOT use alloy band clamps. They are so weak you'll just break them! Regardless of what pipe you have to use get the stainless clamps. They hold up much better and longer. They keep there shape a little better also and seal/grab way better. If you don't have a swell overlap there is Butt-band clamps for 2 identical pipe sections to mate. Again stainless clamps are best. Little flexing means a tougher exhaust and better connection. 

 

Now that your up to date....spend the dang money and get a good exhaust, the $260 special online will work yes but sound isn't great, it doesn't last as long and though stainless is much heavier it's only about 20lbs. Unless your doing a full race build it's not gonna matter... you'll be happy you went for stainless in the end. Exhausts usually go on and stay, make sure your gonna be able to live with it for 5-20 years of ownership when the dodge body is gone and your riding the frame and engine cause it's all that left lol

On ‎8‎/‎25‎/‎2018 at 4:16 PM, Tittle Diesel Performance said:

 I love the deep grunt and burp sound, it just screams cummins! Cheap 4" systems will gain you the same power but it's a little more raspy.

 

Now the MOST IMPORTANT part! The material!!!! This makes a huge difference in sound, no performance gains but the sound change is amazing. 

 

 

Sound is also dependent on single or dual. There is a big difference in sound with a single exhaust on a 1st and 2nd gen. v/s the 3rd and 4th gens. Mostly it is because of the center outlet exhaust manifold v/s the split manifold.

 

My '74 F-350 5.9 Cummins with a center outlet exhaust manifold and duals sounds very similar to a split exhaust manifold of the 3-4 gens. Especially if you use a divided y-pipe, like this:

 

https://www.youtube.com/watch?v=hy8NaAjxP34  Quick video of my Ford exhaust sound.    

Absolutely along with the fact that stacks are usually stainless and of course angles make a big difference. With duals you also have length and bend in differences that effect sound too. 

 

In a high school project a friend and I took a chevy long bed half ton truck, routed the exhaust up into the bed and with a bunch of straight and U sections we made the most idiotic exhaust ever, it spaneded front to back of the bed 11 times on both sides (true dual) and essentially filled the entire bed with exhaust to prove a point on sound waves. No mufflers or cats and it dropped 35db of sound due to all the bends and various angles we used.  Flow wasn't the greatest but the point of the science project was we wanted to weld and goof off but the therory was dampening noise without a common exhaust muffler or cat system. Got an A on it and it cracked like an AK47 lol

Well I have a different type of exhaust question.  Just purchased a used 01 and the exhaust dumps right after the muffler, or resonator.  In front of the rear axle.  I can't imagine that this is good for the Right rear Brake assembly?  Is this stock?  Or is there a piece that is supposed to good over the Rear axle?  It's a 4" exhaust by the way.

 

Thanks

Michael

Edited September 4, 20186 yr by int3man

It suppose to dump out rear of the passenger side rear tire. 

So someone got lazy.  Does anyone know where I can buy the over the axle part and dump portion for a 4" exhaust?  I need to get it out of the Right Rear Axle area.

 

Thanks!

Michael.

54 minutes ago, int3man said:

Well I have a different type of exhaust question.  Just purchased a used 01 and the exhaust dumps right after the muffler, or resonator.  In front of the rear axle.  I can't imagine that this is good for the Right rear Brake assembly?  Is this stock?  Or is there a piece that is supposed to good for the Rear axle?  It's a 4" exhaust by the way.

 

Thanks

Michael

Mine is that way also simply cause it rotted off just behind the stock muffler so I removed the tail section so it wasn't flopping around. I'm going to jamb a steel rod up the muffler to open that little piece of metal inside and make more of a flow thru muffler. Then jamb in a tight fitting piece of pipe inside the muffler and then reweld the tail section back on to clean pipe. 

21 minutes ago, int3man said:

So someone got lazy.  Does anyone know where I can buy the over the axle part and dump portion for a 4" exhaust?  I need to get it out of the Right Rear Axle area.

 

Thanks!

Michael.

Call or go online to Diamond Eye Exhaust. They have those tail sections pre bent in their kits. 

14 minutes ago, JAG1 said:

Mine is that way also simply cause it rotted off just behind the stock muffler so I removed the tail section so it wasn't flopping around. I'm going to jamb a steel rod up the muffler to open that little piece of metal inside and make more of a flow thru muffler. Then jamb in a tight fitting piece of pipe inside the muffler and then reweld the tail section back on to clean pipe. 

 

I always knew you had some redneck in ya. Just did not know how much.

 Steel rod thru the muffler=poor mans magna flow.

Might be easier to just replace the entire exhaust with a new kit. Unknown if you can get the right tail section for length and everything without seeing the existing system and what you've got.

It called ram rod mufflers.

2 hours ago, Mopar1973Man said:

Might be easier to just replace the entire exhaust with a new kit. Unknown if you can get the right tail section for length and everything without seeing the existing system and what you've got.

It rotted at the back end of the muffler is all. So I'm sleeving a new piece to go up inside the muffler long enough to allow cutting off the rot on the tail section which is still pretty good. Then weld it up. Doing it after work when i am already dirty in the evening.

 

16 hours ago, int3man said:

So someone got lazy.  Does anyone know where I can buy the over the axle part and dump portion for a 4" exhaust?  I need to get it out of the Right Rear Axle area.

 

Thanks!

Michael.

IBMobile has one. His stock exhaust is still all in good shape just laying there since he wanted a new System.

 

You might be close enough from where he is to go pick it up. Not sure

Edited September 4, 20186 yr by JAG1

On 9/3/2018 at 4:44 PM, int3man said:

Well I have a different type of exhaust question.  Just purchased a used 01 and the exhaust dumps right after the muffler, or resonator.  In front of the rear axle.  I can't imagine that this is good for the Right rear Brake assembly?  Is this stock?  Or is there a piece that is supposed to good over the Rear axle?  It's a 4" exhaust by the way.

 

Thanks

Michael

Yeah not stock that's called a lazy install. It's not great being the brake line is on the axle tube and the heat pulling can boil the brake fluid prematurely. Best to pipe it out the side or atleast put a turn down that exits below the axle housing but not lower then the lowest point of the drum. Or better yet go for a full system behind the tire like mopar man said. 

If your got a rotted exhaust it's hard to beat a $250 4" alluminized exhaust. It's better then potential CO2 and CO poisoning if you've also got a sweet ventilated factory floor and cab corners