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Discussion Starter #1
Ok, so I am torn on what exhaust to put on the truck. At first I was going to go 5" TBE. Thought bigger is better. But I have been told by several people that 5" is over kill since I am not going to heavily mod the truck. Plus, I have also been told by a few people that with the light mods that I am going to have, that there will not be that much back pressure on the turbo. So therefore it will not spool up as fast as it would with the 4".:thud:

I am looking for any help that anyone can give me in making this decision.

Also, are these statements that I mentioned above true?

Thanks in advance for the help.:thumbsup
 

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Discussion Starter #2
BUMP.

I know I posted it early.
 

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Discussion Starter #3
Am I the only one that has heard these things?

:popcorn:
 

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Ok, so I am torn on what exhaust to put on the truck. At first I was going to go 5" TBE. Thought bigger is better. But I have been told by several people that 5" is over kill since I am not going to heavily mod the truck. Plus, I have also been told by a few people that with the light mods that I am going to have, that there will not be that much back pressure on the turbo. So therefore it will not spool up as fast as it would with the 4".:thud:

I am looking for any help that anyone can give me in making this decision.

Also, are these statements that I mentioned above true?

Thanks in advance for the help.:thumbsup

I have a 5in back and i love it but if you do not plan to heavily mod it then i would use the 4in back.

There is never too little backpressure in a diesel. in my experience when the charger spools you will build more psi when there is less backpressure, however it may take a very small amount of time longer to spool up. just my experience though
 

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Discussion Starter #5
yah that is another thing i have heard.

I originally wanted the FBD 5". I have heard great things about it. But then these other people told me that it might be over kill, so I started to second guess my decision.

I am really looking for a good sound. not too loud. and good performance. I really only plan on putting an intake and exhaust on this truck. it is a daily driver and I just want to let it breathe a little better.
 

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diesels dont need back pressure from what ive read and seen. I cut my exhaust so i was running strait 4"for only about 4 feet under my truck. and my truck spooled up faster and was loud as hell, then when it did when i put my muffler delete pipe on. and youve seen people with hood stacks before.
 

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Discussion Starter #7
Yah, I am just trying not to mod the truck to much, as it is still pretty virgin. and covered under the "so called" full coverage warranty.

But I know that intake and exhaust are the easiest, least complicated mods that you can do to increase performance.
 

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if your going over 700hp then 5" will work great...under that i'd stay with the 4"
 

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only difference between the two is cost, and tone.

5" is a little more bearable for those who dont like the annoying sound of a woman whinning when your truck is warming up in the morning.

other than that you can make in exces of 700hp on a 4" no problem, and see no gains by going to a 5"
 

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4" about 1/3rd the way back the truck then turn into 5" with 5" free flowing muffler. 5" out the back of the truck
Best of both worlds
 

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from what Ive heard 5" will decrease your low end power, some other things that Ive read say that diesels dont need back pressure and you can run whatever. I think that the difference betweent he two is just the tone.
 

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yup, and like i say, what about the guys with 8" stacks.... go 5" ! i love mine !
 

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i like quiet so i used a donaldson m090535 5"and a fbd 5" turbo back same price as 4" kit
 

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I don't understand how having back pressure would be a good thing with a turbo. It seems like back pressure would prevent the turbo from spooling as quick as it could if there were no back pressure. I say go with the 5". That is what I would have bought if my MBRP 4" was not already on there when I bought it.
 

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you can buy a Donaldson m90535 muffler for $90 and the 5" turbo back piping from fbd for less than $300 this is cheaper than 4", quieter , and no restriction . spool up is a non issue
 

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any engine with a turbo wil lperform best with the largest possible, or no exhaust. the turbo itself provides tons of backrpessure; after the turbo, you want the largest size piping you can fit/afford based on your HP goals.
 

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any engine with a turbo wil lperform best with the largest possible, or no exhaust. the turbo itself provides tons of backrpessure; after the turbo, you want the largest size piping you can fit/afford based on your HP goals.
:agree2: completly. you want the exhaust to be as free as possible after the turbo, but that brings up another topic of discussion, the outlet in the turbo is 2.75", so when does making the exhaust bigger have no increase on flow. itd be nice to measure the pressure in a 3, 4, and 5" exhaust at WOT.

as far as the 4" down pipe into 5" muffler back, its pointless for performance, if you were going to make a step in sizes you'd want the 5" down pipe into 4" muffler back, as the exhaust gets further from the engine it gets cooler, more dense, basically smaller, so you dont need the larger exhaust toward the end.
 

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My rig had a 5" straight pipe on it when I got it. It has a nice deep snarl under throttle, sounds like an 18 wheeler pulling a hill. The down side is a nasty drone at certain throttle settings. I'm considering a 5" resonator in place of the muffler delete pipe.

As far as the theory, less backpressure is better, and yes the pipe can get smaller as the exhaust gases cool.

Ops
 

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Exhaust size is only as good as the smallest part it has to go through..
 

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Yeah go with the 5'', you'll be happier with in the long run.. I think I would leave the downpipe a 4'' and then 5'' the rest of the way back. good luck
 
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