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Old 08-08-2007, 04:27 PM
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Another Exhaust question

I've been reading alot of your posts and i'm ready to upgrade to a bigger exhaust. I've decided to go with a 4" turbo back exhaust. My question is does anybody know the difference between the kits with a 3.5" downpipe versus a 4" downpipe. The 3.5" kit claims that it will let the turbo spool up faster at lower rpm's and have more low end torque. Is this true? Anyone have experience with this?
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Old 08-08-2007, 07:03 PM
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to Powerstroke.org. Honestly I don't know the answer. I went with the 4 inch to let out as much exhaust gas as I can to keep the egt's down. I suppose it could even have the opposite effect by causing more restriction the 3.5 downpipe. I could be wrong though

Last edited by vitalidle; 08-08-2007 at 07:08 PM.
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Old 08-08-2007, 07:06 PM
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Since you have a 7.3, most all of them should be a 4" DP and then 4" all the way back. The only time you have issue, is with either an OBS (older body style...pre 99) or a 6.0. The 6.0s will take a 4", but it is not pretty.

to the ORG
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Old 08-08-2007, 07:34 PM
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before i answer tell me what your main purpose is of adding 4 inch exhaust. are you wanting just to get more torgue and pulling power or are you wanting to make it a little quicker
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Old 08-08-2007, 09:45 PM
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LOL He will tell you that the 3.5 down pipe will give you more low end TQ... This is not true... Stick them on the dyno, they are the same... Only thing 3.5 down pipe will have higher EGT's...
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Old 08-09-2007, 05:05 AM
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My main purpose going to the 4" exhaust is to lower the EGt's. But I also would like to retain the torque and pulling power since I do alot of towing with the truck.
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Old 08-09-2007, 05:07 AM
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You will be fine with a 4" turbo back system. Check with the vendors here and any of them can fix ya up.
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Old 08-09-2007, 06:19 AM
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Some better than others though.
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Old 08-09-2007, 09:19 PM
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If you are wanting to lower your egt's you have to stup up to a 4 inch if you get a kit with a 3.5 downpipe you basicaly just bought a 3.5 inch exhaust system. To lower egt's you have to get more exhaust out of the turbo than the 3.5 will alow even though it steps up to a 4 inch on back you need a four inch especially if you ever add more fuel to it you could not tow then your egt's would soar and cherry up your turbo do that enough and you can kiss not only your turbo goodbye but your engine to
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Old 08-09-2007, 09:41 PM
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Quote:
Originally Posted by radicaldiesel View Post
If you are wanting to lower your egt's you have to stup up to a 4 inch if you get a kit with a 3.5 downpipe you basicaly just bought a 3.5 inch exhaust system. To lower egt's you have to get more exhaust out of the turbo than the 3.5 will alow even though it steps up to a 4 inch on back you need a four inch especially if you ever add more fuel to it you could not tow then your egt's would soar and cherry up your turbo do that enough and you can kiss not only your turbo goodbye but your engine to


Your not watching EGT's for the sake of the turbo... Before you will damage the turbo your aluminum pistons will long ago be melted... Just an FYI...
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