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Old 03-23-2004, 07:56 PM   #1
D-Speed 2.5
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Default Catless Midpipe?

Is it possible to have a catless midpipe, i.e. straight pipe, without the sensors? I was thinking of doing a straight pipe for the track and just zip tying the sensors to something under the car.

Is this possible or will it make the computer do funny things or hurt the sensors, etc.? Oh yeah, its a 2000 2.5RS.
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Old 03-23-2004, 07:58 PM   #2
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just have the spots for the o2 sensors made with the pipe. Then get a CEL eliminator for the 2nd o2 sensor. I just got the stromung track pipe myself.
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Old 03-24-2004, 01:47 PM   #3
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Defiantguy is right, you definitely want that first sensor to be in place. The second sensor is merely for testing whether the cat works, but the first sensor is what the ECU uses for adjusting air/fuel ratios (except at WOT) and definitely needs to be there.

So if you use a track pipe, get one with the O2 bungs in place and just use a MIL eliminator on the rear sensor so you won't trip the CEL due to catalyst efficiency.

Shane
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Old 03-24-2004, 05:05 PM   #4
imprezza01
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I gutted a set of cats for a friend, pain in the a$$. But it worked, sounded hollow and was running rich. After about a week CEL came on, wired in a CEL eliminator fixed the problem and never looked back.
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Old 03-24-2004, 08:23 PM   #5
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running rich is a trademart of n/a subaru's. You can just hear it alot more when you have no cats.
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Old 03-25-2004, 01:05 AM   #6
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Cool thanks for the input. I was thinking about getting one made. The reason I asked was because I was under the car the other day and that stock pipe is so restrictive looking compared the size of my Greddy catback section. I might just go with a premade section like the stromung though.
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Old 03-25-2004, 01:23 PM   #7
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After quite a bit of searching, I can't seem to find where I can buy the Stromung or any other catless intermediate pipes for the RS. Does anyone know where I can buy one?
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Old 03-25-2004, 06:35 PM   #8
NicGordon
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Default booya!

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Old 03-25-2004, 09:18 PM   #9
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The midpipe on the RS doesn't have a cat does it? I thought it was a resonator that looks like a cat. The only thing a aftermarket pipe does is increase the diamater.
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Old 03-25-2004, 09:20 PM   #10
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Quote:
Originally posted by mike270
The midpipe on the RS doesn't have a cat does it? I thought it was a resonator that looks like a cat. The only thing a aftermarket pipe does is increase the diamater.
They don't have a cat in the midpipe...it is just a resonator
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Old 03-25-2004, 09:21 PM   #11
Section 8
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Don't hollow out the cats. By removing the material in the cats, you basically produce an expansion chamber that slows down exhaust flow, and then speeds up again on the other side when it reaches the normal exhaust diameter.

You can effectivly produce a standing wave, and at a certain RPM/RPMs this can cause excessive pressure. If you dynoed your car with a hollowed cat, it would likely have jagged spots where standing wave formation occurs.

Leave the ghetto mods in the ghetto. A cheap solution for a clogged cat is not a performance mod just because the cat "isn't there" any more.

As for the poster of the thread, your car will not run in any sort of respectable mannor with out a front O2 sensor in place.

cheeRS,

Greg
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Old 03-25-2004, 11:29 PM   #12
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Quote:
Originally posted by CheezeWeezle
They don't have a cat in the midpipe...it is just a resonator
That is what I thought.....

Quote:
Originally posted by mike270
The midpipe on the RS doesn't have a cat does it? I thought it was a resonator that looks like a cat.
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Old 03-26-2004, 10:54 PM   #13
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Thanks for all the help with this. By midpipe I meant the cat section between the header and the cat back. Right now I have the Borla Header and a Greddy EVO Catback and the stock cat section between the two is what I am talking about. Thanks again. Are there any other premade catless pipes?
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Old 03-26-2004, 11:16 PM   #14
Section 8
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TWE will make anything that you want.

Tell them that Section 8 sent you.

cheeRS,

Greg
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