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Old 01-26-2013, 07:07 PM   #1
Serkan
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Member#: 180514
Join Date: May 2008
Chapter/Region: E. Canada
Location: Windsor
Vehicle:
2004 Sti White

Default upsizing muffler pipe diameter

I have the turboXs magnaflow cat back setup on my car. I have heard so many exhaust but this is my favourite.

The downside for this setup is it goes from 4" bell mouth downpipe to 2.5" axleback. With a bigger turbo setup I definitely need 3" exhaust all the way.

Is it possible to weld 3" piping to Magnaflow muffler ?

Are the internals still going to restrict and making the modification useless ?

Thanks.
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Old 01-28-2013, 09:34 PM   #2
bebesito21
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5862 ...baby boosted

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I think its been proven that there isn't a difference up to x whp between 2.5 and 3" pipe

With that said nothing is stopping you from cutting and substituting 3" pipe however if the muffler is 2.5" then its pointless and u will have to swap the muffler to get a true 3" exhaust

My .02
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Old 01-28-2013, 09:38 PM   #3
bugeyesubie
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2002 WRX
Silver STi swap 380wph!!

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Most rally cars in the North American rally circuit that are all over 400 whp run 2.5" exhaust. I'd say. Stick with 2.5"
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Old 01-29-2013, 11:34 AM   #4
DeleriousZ
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To answer your question, yes it is possible. You can pick up a 'reducer' to stick between the two different diameter pipes. You'll need to cut some of the pipe pre-muffler to allow for the added length of the reducer.

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Old 01-29-2013, 03:44 PM   #5
Serkan
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Chapter/Region: E. Canada
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2004 Sti White

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I don't want to do this if there is still going to be a restriction inside the muffler.

I guess I will just sell this and get a full 3" catback.

Thanks.
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Old 02-04-2013, 12:23 PM   #6
Serkan
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Location: Windsor
Vehicle:
2004 Sti White

Default

Ok, I bought a 3" fujitsubo jasma cat back.

Even tho it has 3" piping if you look inside from the muffler tip there is 2.5" diameter piping in there ?

I want to know how are 3" mufflers are designed inside.


If i can get same performance by making the magnaflow muffler 3" than I want to stick with it rather than using another 3" cat back has the same restriction in the muffler.
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