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Old 05-14-2009, 01:35 PM   #1
sittinsideways
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Default cat ?

would it just be cheaper for me to have a shop make me a cat rather than buy one from ebay. i have a pair of borla headers sittin in my room.
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Old 05-14-2009, 01:40 PM   #2
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do you mean a cat-section? with or without a cat? be more descriptive.
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Old 05-14-2009, 02:06 PM   #3
sittinsideways
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alright maybe im lost on this. i got the borlas. im a have a shop make me a pipe 2.25. from what i have read people recommend a high flow cat can a shop just make me one or would it be better to purchase one from a company? if im way off then please tell me so.

Last edited by sittinsideways; 05-14-2009 at 08:14 PM. Reason: words
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Old 05-14-2009, 02:12 PM   #4
formula91
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emissions wise, having a cat of some sort would be better. The cheapest option might be to have them fab up a new pipe for your old cat without having restrictions.

The old cat, unless it's REALLY OLD and used up, does not restrict flow much.
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Old 05-14-2009, 02:26 PM   #5
sittinsideways
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alright cause im kind going off this guys words http://forums.nasioc.com/forums/show...nstall+headers in this thread but what i guess i dont get is what is a " Used 2.5RS Catpipe " i guess thats what gets me. cause i have the headers and exhuast but the mid section is where i get all confused. should i buy one or have one made or what?
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Old 05-14-2009, 02:28 PM   #6
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Buy a used 2.5rs catpipe. If you do, you'll have to get an o2 extension for your rear o2 sensor, though.
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Old 05-14-2009, 02:58 PM   #7
sittinsideways
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but what is a catpipe is it the mid section or the front portion. im lost as all he**
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Old 05-14-2009, 04:21 PM   #8
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Headers aka Exhaust Manifold is the first piece. This bolts to your heads.

Cat Pipe comes next. OEM cat pipes usually come in two sections because there are two cats, so that if one cat dies you don't have to replace both cats. Hi-flow cats are usually one piece. Track pipes are just a pipe and eliminate the cats altogether.

Next is the Midpipe. Usually there is a resonator or even two in the midpipe.

Finally the Axleback aka Muffler. Less commonly called a diff-back or backbox. I think we all know what this is. If you don't, then you shouldn't be working on your own car.

The Midpipe and Axleback/Muffler together make up the Catback.

This is all specific to 93-07 Impreza's. I haven't had a close look at 08+ NA exhaust plumbing.

Hope this clears things up!
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Old 05-14-2009, 04:33 PM   #9
sittinsideways
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sure does thanks
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Old 05-14-2009, 04:48 PM   #10
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Dont expect a reputable shop to put on a used cat by the way, it is very illegal and carries a large fine
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Old 05-14-2009, 04:50 PM   #11
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im getting headers too you need a 2.5rs catpipe,

you probably COULD get a shop to extend your catpipe or something of that sort to fit with the headers but i dont know. The borla headers were made for 98-05 not 06+ so we need their catpipe to work.


i think OP is asking if he could EXTEND his catpipe to fit the headers
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Old 05-14-2009, 04:51 PM   #12
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you need the one on the left

anyone have pics of what an 06--07 catpipe looks like? im interested too
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Old 05-21-2009, 02:47 PM   #13
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so a 05 rs cat pipe will bolt directly to my catback, as is with no modification, i want to make sure because i really want new headers
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Old 05-21-2009, 11:45 PM   #14
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Quote:
Originally Posted by acemyles2.5i View Post
so a 05 rs cat pipe will bolt directly to my catback, as is with no modification, i want to make sure because i really want new headers
Nope. The only people that make a cat pipe that mates Borla/replica headers to the factory 06/07 catback is rallisportracing.com
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Old 05-22-2009, 09:55 AM   #15
acemyles2.5i
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ahh i figured there wasnt an easy way out (or a cheap one)
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Old 05-22-2009, 10:08 AM   #16
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Quote:
Originally Posted by blk6s View Post
Nope. The only people that make a cat pipe that mates Borla/replica headers to the factory 06/07 catback is rallisportracing.com
or any reasonably competent exhaust shop will bend up something to mate your borla header to the rest of the exhaust.

It's cheaper than any premade solutions people always go on about.
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Old 05-22-2009, 12:13 PM   #17
acemyles2.5i
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ya i thought about that, theres a pretty good exhaust shop about 15 minutes away from here, maybe ill call them up and see what they can do.....i think these borlas will sound pretty good since i got my new stromung
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Old 05-22-2009, 06:01 PM   #18
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Quote:
Originally Posted by acemyles2.5i View Post
ya i thought about that, theres a pretty good exhaust shop about 15 minutes away from here, maybe ill call them up and see what they can do.....i think these borlas will sound pretty good since i got my new stromung
Hold on, now im confused. you are trying to hook up the borla headers to the stromung catback or the factory catback?

Yeah a exhaust shop can do either cheaper than a good premade catpipe but the exhaust shop wont use stainless and the welds wont be pretty.
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Old 05-22-2009, 08:45 PM   #19
blk6s
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Quote:
Originally Posted by RaceFaceXC View Post
Hold on, now im confused. you are trying to hook up the borla headers to the stromung catback or the factory catback?

Yeah a exhaust shop can do either cheaper than a good premade cat pipe but the exhaust shop wont use stainless and the welds wont be pretty.
Exactly. Premade HFC pipes vs. the local exhaust shop are apples and oranges. Exhaust shops don't carry stainless steel, don't have expensive mandrel benders (they use crush benders), like to weld pipes together instead of using proper flanges and gaskets, plus I believe its illegal for them to remove or even replace a operational cat. Then theres the fun of driving down to the shop with open headers, and no o2 sensors.
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Old 05-23-2009, 01:54 AM   #20
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Quote:
Originally Posted by blk6s View Post
Exactly. Premade HFC pipes vs. the local exhaust shop are apples and oranges. Exhaust shops don't carry stainless steel, don't have expensive mandrel benders (they use crush benders), like to weld pipes together instead of using proper flanges and gaskets, plus I believe its illegal for them to remove or even replace a operational cat. Then theres the fun of driving down to the shop with open headers, and no o2 sensors.
on the contrary, the shop that I had my catback done at had a mandrel bender, used a flange, and will use whatever grade steel you like (stainless wouldve cost another $100). Finally, who cares how pretty a weld is, it's under the car where no one will see it. As long as its structurally sound, it's fine in my book.

Don't dismiss it until you've found out what's local to you.
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Old 05-23-2009, 02:09 AM   #21
blk6s
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I stand corrected
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Old 05-23-2009, 02:34 AM   #22
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i just took the cats out of my 95 impreza. i thought i would get a check engine light but i didnt. the car seems to run fine
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Old 05-23-2009, 09:21 AM   #23
SubieGenius
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cats? WHAT CATS? lol
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Old 05-23-2009, 11:22 AM   #24
Aegean93L
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Quote:
Originally Posted by nerally View Post
i just took the cats out of my 95 impreza. i thought i would get a check engine light but i didnt. the car seems to run fine
95 was the transition year from OBD1 to OBD2.

If your car is OBD1, it only has one O2 sensor, and it's before the cats, so that's why you don't get a CEL.

If it's OBD2, well, you just got lucky!
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Old 05-23-2009, 11:30 AM   #25
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Quote:
Originally Posted by nerally View Post
i just took the cats out of my 95 impreza. i thought i would get a check engine light but i didnt. the car seems to run fine
i tried on my 07. bad idea the car ran like crap
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