Which one is more restrictive...cat or muffler?

[Arkapigdiesel]

I'm going to start off with removing one and will eventually remove both. Question is, which one restricts exhaust flow the most... . the cat or muffler?



For those of you who have removed the muffler..... is there any reason to remove the resonator behind the muffler?

 

[Bodie]

Some buddies of mine have made a cut-away of the stock muffler and, I would say it is more restrictive than the cat. Just by looking at it. I wouldnt know a easier way to tell which is more restrictive... ... . unless you have access to a huge flow bench.

 

[WUnderwood]

I would say the factory muffler is

 

[nickleinonen]

cat once it has some miles on it. .

 

[2broke2smoke]

after seeing the inside of a cat i say cat ...



do a search ... someone had a post with a high def photo of a cat's interior ...

 

[JVolpe]

Well I have no real flow data on either muffler or the cat. I have only SOTP and performance (boost, EGT, etc. ) to go by. I did post a picture of the inside of the cat and will attach here. Just looking at a muffler insides and the cat insides I would think the cat would be more restrictive. But my real world SOTP meter and performance and engine gauge monitoring experience does not back that up. Replacing stock muffler with high flow muffler made considerable more/measureable flow and performance than when the cat came off. There seemed to be no real or measurable difference other than sound and smell when the cat was removed. Just my experience, of course it is still off.



The picture is looking through the cat into direct, bright sunlight. The ceramic honeycomb fills the entire large diameter section of the cat.



#ad

 

[Signal73]

The cat is like a TAG, but for the exhaust... #ad

 

[WBarker]

I would say the cat is because of the tiny lil holes that your exhaust has to go through to get to the muffler

 

[DrDiesel]

My . 02 would be the muffler. Today`s cat `s are Hi-Flo high performance.

Looking at them tells you nothing of flow characteristics.

On car gas engine`s, I have found the muffler to be the biggest restriction.

 

[MSchweigert]

As for which has the greatest flow restriction you might check out this post from another site.

http://www.carsondodge.com/Forums/showthread.php?t=1&page=6

 

[Mark Craig]

Arkapigdiesel,



Definelty the muffler, when folks get a muffler and cat pipe from us they have done muffler only or cat only and the result has always been the muffler gets you twice the EGT drop as only doing the cat. So to me in an un scientific test method tells me the muffler is a larger restriction than the cat. Now of course the best way to go is do both at the same time!! By the way the resonator after the muffler on Mega' cabs doesn't present any real restriction at all.



Mark @ DPPI

 

[DerekW]

IT DON'T MATTER just get rid of both of em. they eat power and mpg and at same time can kill your engine thanks to high EGT. So grab your sawzaw or the one in your neighbors shed when he not home and fix your trucks "problem". swell up some 4" pipe to fit over the ends of the stock pipe make sure the angle on the back of the tail pipe is right and burn it in. then take some 3/8" solid stock stick in is a vise and bend it in the shaped of a hanger then burn that in. then Fire it up and you should have a **** eating grin on your face thinking "I'm badass now, lets go for a ride". Just trust me your like it, its not loud in the truck with the windows up, I can talk on the free crappy cell phone. I have been on trips where I drive 8 hours non stop and it doesn't bother me at all with the windows up. I may sometimes roll the windows down and gas it to wake myself other wise everyone should do it. I gained 2 mpg towing 11,500lbs