Ok diesel guys...riddle me this.....

[NMStickFlinger3]

What in the world is back pressure?! My truck is straigh piped with 5" pipe under the truck, to 4" stack kit, up to dual 6" stacks out the bed. I recently bought this truck the way it is. My buddy said I may be getting some back pressure due to the exhaust system set up the way it is.....but I dont even know what that is!! Any help out there??

[Quackerbox]

I cant explain it but Ive always been told a little is better, especially for the cummins motors. Friend of ours owns a performance diesel shop and says straight pipes aint what they are cracked up to be unless you want to wake the neighbors. I have a plain ole 4" stainless magnaflow kit on mine muffler and all

[ratterrier]

Back pressure is coming from the 4 inch necked downed kit, sounds horrid, you should rip off all of that junk and just run a 5 inch exhaust and forget about those gay stacks that burn everything that touches them. 5 inch into 4 inch into 6 does not make sense, should be 5 all the way so the same flow and not necked down to 4 inch, its like a water hose with a knott in it.......

[BuffaloHump]

Back pressure is coming from the 4 inch necked downed kit, sounds horrid, you should rip off all of that junk and just run a 5 inch exhaust and forget about those gay stacks that burn everything that touches them. 5 inch into 4 inch into 6 does not make sense, should be 5 all the way so the same flow and not necked down to 4 inch, its like a water hose with a knott in it.......

and all the people said.....

[NMStickFlinger3]

I just took a closer look under the truck....heres what it looks like to me. 4" downpipe from the turbo opened to 5" to where the stack kit starts. then back down to 4", up through the bed, split to both sides and into 6" stacks. ***?!?! I think Im gonna sell this exhaust and just get a 4 or 5" turbo back kit.

[Extremebowman]

I just took a closer look under the truck....heres what it looks like to me. 4" downpipe from the turbo opened to 5" to where the stack kit starts. then back down to 4", up through the bed, split to both sides and into 6" stacks. ***?!?! I think Im gonna sell this exhaust and just get a 4 or 5" turbo back kit.

The 6" stacks are just for looks, they have no real purpose. Install sounds normal until they necked it down to 4". The biggest plus for my use of going to 5" exhaust is to expell the burned gasses more effeciently and faster to keep the EGT's down. Your on the right track changing to straight 5"

[txmuleyman]

Back pressure is coming from the 4 inch necked downed kit, sounds horrid, you should rip off all of that junk and just run a 5 inch exhaust and forget about those gay stacks that burn everything that touches them. 5 inch into 4 inch into 6 does not make sense, should be 5 all the way so the same flow and not necked down to 4 inch, its like a water hose with a knott in it.......

If its a stock turbo he can't start at 5inch.so just run straight with a stock exhaust.and my stack said your pipe is gay.

[NMStickFlinger3]

So, is it better to straight pipe the exhaust, or get a kit with some kind of muffler or resonater or something?? I also have this posted on CumminsForum.com and there seems to be a real split among people who are for and against back pressure, and what causes it.

[txmuleyman]

Get on competitiondiesel.com.They will give you everything you ever wanted to know.

[Tommyh]

are you going to have holes in your bed after removing the stacks?

[NMStickFlinger3]

are you going to have holes in your bed after removing the stacks?

Just one 4" hole on the right side. Figure I'll patch it, and get a spray in bed liner. Better than not having that bed space and the pipes burning everything they touch!!!

[Dale Moser]

It's not going to change enough to notice.....if at all. You can move as much exhaust through the 4" section going through the bed as you can through the 4" downpipe.

[mchildress]

Get you a flow through muffler inline they are cracking down when getting them inspected with just a straight pipe. It doesn't matter how loud it is as long as there is something inline that resembles a muffler.

[jkg2003]

since you are running 4 inch and bigger, you will not notice any back pressure because of the neck down from 5 to 4 and back, the pipe is big enough that you arent filling it up with exhaust so no pressure change is happening, but I x2 the notion of getting rid of the stacks, for one it looks cheezy and you will burn the fire outta yourself, plus more bad space...as stated before the stock turbo is a 4 inch outlet and most ppl go to a 5 inch pipe just for sound, the bigger the pipe the louder it will be....

[NMStickFlinger3]

Well, its definitely LOUD!!! Kinda obnoxious really!! I listed the whole set online for sell....I can only buy something different if I sell what I have!! Thanks for the input all!!!