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The 6b from a dodge came with 3'' you'll be fine ,you can always go to 4'' once you get past the firewall or t-case if there is room.

Scott
 

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The larger the diameter of the exhaust, the more flow potential but also a reduction in backpressure. Exhaust tone will be altered but loudness will be more effected by muffler choice (if any). Decible wise, it'll go up a couple points - nothing dramatic.

- based on exhaust tests with non-4bt vehicles; your individual results may vary -
 

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Discussion Starter · #5 ·
So 3'' should be good, right on,...anyone know where to get turbo outlet gaskets for a Hx35W? Or what the oe part number is to get if from Dodge?
 

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You dont need a gasket if you use a good flat piece for the flange. Dodge will carry them if you want one.

3" should be fine. There is very little need for the big exhaust you see on alot of these trucks. Unless you are running a turbo larger than an HX35, 3" is just fine. 3.5" is large enough for well over 500HP. I run a single 3.5" exhaust on my 700HP turbo gasser. 4" is good to close to 1000HP and 5" for over that. Not many 1000HP 6BT's running around on the street, but there are alot of 4" & 5" exhaust systems :).

The whole deal with the big exhaust is for EGT and quick spool. You actually only need an oversized pipe about the first 2-3' from the turbo to give the air a chance to decompress and achieve a linear flow. So, most of these big exhaust systems could be big at the elbow and turn down, then go back to a 3-3.5" system. Just a little basic turbo fab info....
 

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I wouldn't assume 3" is fine, plenty of factors could affect egt. I would put an exhaust gas temp gauge in the manifold pre-turbo and then decide if the exhaust needed to be larger...
 

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exhaust

would a 4inch setup hurt performance. i have the option of getting a free factory 2004 dodge exhaust that i could adapt to my jeep. but i would have to cut and weld. would the welds affect the flow and is 4inch to big.
 

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It won't hurt the system...but it would be a tad overkill. But, it IS free! And don't worry about the welds. A little bead is negligable. A crimp-bent elbow suffocates more than a weld bead (assuming the factory did it the quick/cheap way). Mandrel bent is best, but the 4" will take the slack.
 

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great i have a 2 1/2 output on my turbo just use a couple of reducers you think
 

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great i have a 2 1/2 output on my turbo just use a couple of reducers you think
These bolt to a hx35 flange and turn it into a hx40 size flange allowing you to bolt a 4" downpipe to it, worked for me. You can get them from piers diesel.

Gaza
 

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is the hx 35 what comes factory on the 4bt
 
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