Advantages of 4in exhaust

[JEmmons]

I am ready to put on 4in exhaust. Can anyone with experience give me an idea of the differences between stock and 4in. Currently I have factory without the muffler and an empty cat. What will the sound difference be?

Will I notice and difference in hp, spool up, fuel mileage?



All responses are appreciated.

 

[JTeague]

Differances

I have already done this swap with my truck and the only differance between a 4in straight pipe and a 3in staightpipe on my truck was the sound. It is a lot deeper in tone. I didnt notice any change in EGTs or fuel milage. I think the 4in would be more benifical with a bigger turbo and on trucks with over 400 HP. I dunno? Hope this helps.

 

[LarryB]

I think JTeague is correct re HP.



Within reason, the larger the pipe the slower the sound waves travel, giving a lower tone.

 

[John_P]

JEmmons:



I have the 4" Diesel Dynamics exhaust on my 96'.



Contrary to what everyone else said I noticed alot

of difference after taking off my 3" system. However,

my "cat" was plugged up pretty bad after 65,000 miles

so that was some of the difference I'm sure.



I noticed that my EGT's were NOT as high as before.

Also, my throttle response seemed better. The

sound of the DD system is "throaty" down low with

a real nice "tone" at about 2200 RPM. It is louder

than stock, but not offensive. I can carry on normal

conversations inside the cab and I can hear my radio/

CD. I have the Walker 21471 muffler on the DD system.

If I gained any H. P. it was very minimal. Joe Donnelly

did alot of testing on this and has said the H. P. gain

is small if at all.



Hope this has helped you some.



-----------

John_P

 

[Snow man]

I was at 360 hp at the wheels when i changed to 4",I think it lost low end power,and everywhere else it was the same,EGT;s dropped s little,maybe 50 degrees WOT,if i had it to do over, i would have left the stock exhaust on,no drone,or rattles,and good power,i cant get this 4" system to stop rattling in neatral for anything,it buzzes like crazy,put it in drive,and its gone.

 

[rhoads]

4" exh

Come on guys , some didnt pay attention in the lower years of school BUT to put it in simple term's go to the out side faucet hook up that 1/2 inch water garden hose then go to the end and hook up a 1" hose and see if it truley comes out faster under the same pressure.

You will find neg $$ in your pocket--- and +++ $ in vendor pockets!!!

First port the heads bigger inj'rs, stream line manfoild, upgrade turbo---then -- and only then--install bigger escape route. .

You are your only warrenty station---and comptroller(bean counter) >