A niiiiice long post about Exhaust Systems...

[LikeaRock14]

Well, I decided to make a nice long post about exhaust systems for newer GM trucks.

 

Pipe Sizes:

 

Is bigger always better?

Don't be fooled! Bigger is not better! Many people think that having the biggest diameter pipe is the best way to make power.

Not true. Due to a variety of factors, extensive testing is required. Some manufacturers claim even higher horsepower numbers. It is a fine line to reduce backpressure while maintaining good exhaust velocity. It is not about getting the biggest pipe, it is about getting a more efficient pipe diameter while maintaining exhaust velocity. There has to be a balanced design to enhance the maximum engine output, exhaust gas velocity, and sound. For example, imagine blowing air through a straw (comparing it to a smaller diameter pipe). This would take time to release all the air from your mouth, and you would feel pressure in your mouth while doing so. Now imagine blowing air through a paper towel roll (comparing it to a larger diameter pipe). You will relieve all your air much faster and feel little or no air pressure in your mouth because of the larger capacity of the tube. This is why it is important to get the correct size piping in order to relieve backpressure while maintaining thermal efficiency. In general, the following guidelines should be followed for street applications.

2" tubing up to 100 hp per pipe

2.25" tubing up to 160 hp per pipe

2.5" tubing up to 200 hp per pipe

3" tubing up to 300 hp per pipe

 

Another thing with pipe diameters is sound issues. Bigger might look cooler and seem louder, but it's not always the best as far as sound goes. a smaller diameter pipe size, i.e, reffering to a 4.8 ltr. or 5.3 ltr. GM, 2", 2.25", will make a slightly quieter, sort of raspier exhaust sound. 2.5"-3" exhaust tubing will produce a slightly louder sound, but may produce a wooshy, echo sound. If this is what you prefer, so be it goes on your truck. It's all about preference.

 

Stainless VS. Aluminized:

 

The main difference between the two is pricing and the outer shell of the mufflers. Stainless Steel cost more than Aluminized Steel. The Stainless steel mufflers have a polished stainless steel shell and are 100% stainless construction. Stainless steel is better looking and will never rust. Nothing looks better or lasts longer than stainless steel. Magnaflow aluminized mufflers have stainless internals and necks but have an aluminized outer shell. Also, the aluminized steel has only a protective coating that, if scratched off, may rust.

 

Does an aftermarket exhaust void my factory warranty?

 

NO. It's also illegal for a dealer to deny you the OE warranty because you have changed the exhaust system. This is an often asked question. But you will need to be armed with some basic information.

 

Under the Magnuson Moss Warranty Act of 1975, 15 USC, 2302 and Clean Air Act 42 of USA code 7541, you have rights.

 

This legislation basically states that:

 

In order for a dealer/manufacturer to deny a warranty on a claimed part, they must PROVE that the part YOU installed/had installed DIRECTLY caused the failure of the part on which you’re claiming the warranty.

 

Horsepower gains:

 

It's different for every car, but typically expected gains are in the average range of 10%.

 

Replacing the muffler/exhaust with a free-flowing, aftermarket muffler will help your engine increase power by being able to expel exhaust gases quicker. This creates less workload for the engine, makes it run more efficient, and results in better power.

 

What about mileage???

 

 

YES, a better performing engine uses fuel more efficiently, if driving conditions and tendencies are similar. However, it is not a guarantee. It's different for every vehicle. A typical gain, with the right exhuast on a newer GM vehicle ranges from 2-4 m.p.g, depnding on the way you drive too

 

Dual out vs. Single out:

 

In most cases a single exhaust will give you better torque and horsepower. The exception would be a heavily modified engine. Dual out looks cooler usually though

 

Now for the biggy:

 

Performance from an Aftermarket exhaust:

 

Exhaust System preference:

 

For more performance, a straight through performance muffler, like Magnaflow, Dynomax, or Borla is the way to go.

For more of a performance "sound", go with Flowmaster or Spin Tech.

 

We'll pretty much sum it up here:

 

For a loud, deep exhaust, a 14" Magnaflow, Borla Pro XS, Dynomax Ultra-Flow, Spin Tech Pro Street, or Flowmaster 40 series system is right for you. Magnaflow and Borla will be deeper, having them be a straight0through exhaust system, while Spin Tech or Flowmaster will make a slightly more mellow, more aggressive sound. These systems are reccomended for someone who wants a full-out performance sound exhaust

 

For a more mellow deep exhaust system, a 50 series Delta Flow Flowmaster, 18" Magnaflow, Spin Tech Sport Truck/SUV, or Borla turbo muffler would be right for you. Quiet while cruise, but it's there wehen you want it. This is a more reccomended system(s) for someone who would like to hear their exhaust, but it is also their daily driver.

 

For a so-called "slightly" louder than stock exhaust, a 24" Magnaflow, 70 series Flowmaster, or Spin Tech Sportsman Street or Truck/RV Spin Tech is right for you. One of these applications would be great for someone who tows frequently or just is looking for better mileage along w/ a slightly louder than stock exhaust, nothing that is overwhelming but is there only when you really want to hear it.

 

I hope this helps a friendly few!

[dcnfrost_69]

LikeaRock14,

 

That is well spoken of! This information should be in the Guides section for people that have questions in aftermarket exhaust system on their fullsize trucks.

 

I plan on buying an 04 Sierra ext. cab w/ 5.3 V8 this summer and can't decide on which brand of aftermarket exhaust I want. It's either Flowmaster 50 series SUV or Magnaflow. I want to get the whole system and I don't want the exhaust loud outside and inside. I want to get an exhaust that is mellow and deep while quiet from the inside when crusing. My dad will be driving the truck sometimes and I know he doesn't want to hear the loud rumbling sound when he's driving. In exchange, I will be driving his 02 Tacoma Double Cab TRD.

 

From your exhaust system perference, the 18" Magnaflow and the 50 series Flowmaster are my choices in mellow, deep, throaty sound while interior resonence is low when crusing.

 

I am a sucker in duals rear exits b/c of the looks so my question is, when I get the exhaust system, the piping I should get is 2.5" outlet? With that, I won't loose any power in HP and torque? As for the tips, I can get any size I want or I should match the outlet size? I was thinking 2.5" dual rear exit with 3" tips.

 

The sound clips from Flowmaster and Magnaflow website are just the exhaust system alone or with intake, too? I really like the sound of the Magnaflow website of the 04 GMC Yukon launch video.

[LikeaRock14]

Yeah, that really is an awesome sound.

 

I'm not 100% sure, but I imagine that the systems are just the cat-backs themselves, no other aftermarket performance items.

 

I'd reccomend since you're dad will be driving thr truck, and just for a slightly more refined sound while cruise, while losing slightly less torque, would be 2.25" out. Tips are the persons preference, along with the muffler. I just try to help, that's all.

Anyways, an 18" Magnaflow would sound awesome on a 5.3, as in the Magnaflow clip. I'm partial to the Flowmaster tone myself, i know they are'nt the best but d**n they have that sound part down good. A 50 series would be more aggressive, little more mellow. When you ROMP it ohh it sounds nice.

Magnaflow will be a little bit quieter at cruise inside, so since your dad will be driving the truck too, I'd reccomend the Magnaflow. It seems like its more of a sound issue for you, so yeah...

 

It usually goes like this : For sound, people go Flows

For power, or for a quieter sound: people go Magnaflow

[Scott02Z71]

Great Post! I do only have one thing to add (not trying to bash or anything). Stainless steel WILL rust if it is not properly done. IF you were to use cast or iron hangers or have ANY other "rustable" steel touching it, the stainless WILL start to rust. But if you use the proper hardware, stainless WILL last as long as the truck!

 

Just my thoughts!

 

Scott

[rbb0002]

I have to say, you just helped my decide on getting a single in/ dual out, Flowmaster 50 Delta Flow for my '99 5.3 Sierra. I am going to stick with the 2.25" pipes and put 3"/ 3.5" tips exit on the rear corners.

 

Thanks

 

Bob

[LikeaRock14]

Scott: That's true, I was just basically referring to full stainless, i.e a cat-back, but that is absolutely true

 

And Bob: Glad I helped!

[Scott02Z71]

Yea, I just wanted to warn some that wouldnt know. Ive ordered supposed "full stainless systems" from some places and got some crap hardware and ended up with rusted systems.

 

Scott

[SportyShorty]

Flowmaster=increased fuel economy....Umm not in my case bacause just heaing it makes he hammer down even harder! Nah, I was getting 22mpg with my 4.8 last summer cruising 55mph back and forth to work.

[LikeaRock14]

LOL, that's why I said

A typical gain, with the right exhuast on a newer GM vehicle ranges from 2-4 m.p.g, depnding on the way you drive too

[DMAX Daddy]

One thing, bigger is better for reducing exhaust temps in diesels. Going from 3 1/2 to 4 inch on my DMAX dropped my loaded pulling temps (similar loads and ambient, not exact situations) about 200 to 225 degrees.

[LikeaRock14]

Yeah, I read that somewhere else too. That's a hellofa lot when you think about it!

 

(I was reffering to gas though lol), but everything helps!

[Red2500HD]

Horsepower gains:

 

It's different for every car, but typically expected gains are in the average range of 10%.

 

Replacing the muffler/exhaust with a free-flowing, aftermarket muffler will help your engine increase power by being able to expel exhaust gases quicker. This creates less workload for the engine, makes it run more efficient, and results in better power.

 

 

I enjoyed your article regarding mufflers....very interesting. I have one question regarding your quote above. You talk about HP gains, but what affects do different mufflers and pipes have on torque? I have been told that you need a certain amount of back pressure to maintain torque levels. Can you expand on this?

 

For instance.... The stock muffler in my 6.0 liter has dual input pipes of 3" being restricted as it enters the muffler to two 1 3/4" inputs. the dual 3" out put pipes are realy only one functioning pipe as the other one is coming from a totally closed chamber in the muffler. The dealer says that this amount of restriction in exhaust flow is necessary to achieve the level of torque the engine puts out. Is he right, or full of sh*t?

[Machine]

One thing, bigger is better for reducing exhaust temps in diesels. Going from 3 1/2 to 4 inch on my DMAX dropped my loaded pulling temps (similar loads and ambient, not exact situations) about 200 to 225 degrees.

The decrease in temp you experienced can't be totally associated with your new 4" pipes. You have a new, less restrictive muffler that offers most of the improvement.

 

I straight piped my stock 3.5 pipes and also noticed a huge difference in temps. i now run a 4" setup with a straight thru muffler - - the temps are almost the same as the straight piped 3.5 - a tad cooler. But you're right, less restriction is better for a turbo diesel.

[DMAX Daddy]

true Machine, true, I had a lot less restrictive muffler.

 

What really helped even more was taking off the Catalyic Convereter

[LikeaRock14]

I don't know how much more I can expand upon the pipe size and muffler subject...I hoped the straw vs. paper towl thing would be a good enogu analogy I'll think of some way to explain it further for you tho

Dolan