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Old 08-23-2003, 03:46 PM   #1
Zen
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Join Date: Nov 2001
Location: Toronto "spd frk"
Default Running Catless

Well, the search function seems to not be working for me.
I would like to know if running catless would cause a CEL (im pretty sure it will).
Would there be any gains by going straightpipe instead of going with a high flow cat? If anyone out there actually has experience with this then give me your experiences and opinions.
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Old 08-23-2003, 04:13 PM   #2
Slack
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Default

Pros- Cheap, Best performance, loud

Cons- CEL, have to swap in stock cats to pass emissions (if you have to), loud


I don't have a straight pipe, but I do have a high-flow cat section. It flows way better than stock, but a straight pipe would obviously flow better. I know kostamogen<sp?> had one on his car and it is insanely loud. But all-n-all, it can be the best for performance. Do you have a catback or headers to compliment it? Replacing one section of the exhaust still leaves a bottleneck. Replacing the entire exhaust is worth it, especially if it is all custom made at a shop (usually cheaper).


Mick
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Old 08-23-2003, 04:34 PM   #3
Zen
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If i were to go catless I would probably get some techworks engineering headers. They start at 2.25 and then open up to 2.5, then custom make a 2.5 catless midpipe to connect up to my 2.5 scoobysport catback.
I would probably find a way to tune it all in there so I wouldnt get a CEL.
Opinions?
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Old 08-23-2003, 04:48 PM   #4
Dr. Morbid
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I went the custom exhaust route and got a 2 1/4" straight pipe leading a an APEXi N1 Turbo. Before that I just had a Ractive carbon fiber muffler but that cracked due to poor design (condensation + freezing temp= dumb ass at the CAD table). The switch was extremely noticeable and well worth the expense.

Point 1 - I have never had a CEL.

Point 2 - The muffler itself is known for being loud, the muffler with a straight pipe is insane. I bought the silencer for it for long trips and recommend looking into the same as there are several brands that offer a silencer as an option. As far as Greddy saying they are so quiet in all their print ads, it ain't so in the real world and they don't make a silencer. (some of my friends have Greddy axle backs, awesome sound, but the interior drone will have you looking for ear plugs after 30 mins.)

Point 3 - It has an excellent sound to it (a la Subaru rally- esque, very deep and low) but that sound carries for several BLOCKS. Read again: BLOCKS.
This is no joke, under hard rev conditions I can be clearly heard as much as 4 blocks away. With tact I can make it gently burble and not annoy everyone around me, but it took time. With cat and resonator removed the Scooby engine sounds like it means business. My 1.8L sounds like their is some major ponies under the hood and due to that I'm generally left alone by red light racers.

I would do it again without hesitation. Fuel economy improved, power improved (a lot, I can now chirp my tires into 3rd with this improvement) and the drawbacks are neglible.

Hope this helped. Feel free to ask anything more specific if I missed something.

(The muffler was $500 and the custom exhaust system and
install came to $600, that's in Canadian so adjust accordingly)
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Old 08-23-2003, 09:21 PM   #5
JewPac42
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I too think I am going to go catless, but I want to see how loud it is before I make my final decision.
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Old 08-24-2003, 10:47 AM   #6
dynoguy
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i'm catless now . i went with a borla header thru gutted cats and then with a muffler shop made 2.25" cat back w/flowmaster muffler. interior sound is nice not loud at all exterior sound i am not sure how loud it is i am told it is some what loud but not in a honda ricey way. but i do get a cel every other day or so (cat ineffiecy) but i have a scaner so i just reset it when i feel like it.

i put the cat back on first and gutted the rear cat first which didn't get to many cel's once a month or so ( i drive 80+ miles a day/6days aweek). when i installed the borla is when the cel stays on about every day. but by this time next year i should be on a stand alone ecu of some sort.

yea yea i know the air we breath and all, but it's fun to be a kid again


mike kasch
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Old 08-24-2003, 11:13 AM   #7
Bobalouy
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I am haveing my 2.25 catless pipe made right now, along with a mid-pipe, and then I am going to use the stromung muffler. Hopefully it wont be to much louder. I will try to post some sound clips when I get everything installed.

Anthony C
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Old 08-24-2003, 11:58 AM   #8
NC2.5RS
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Im catless right now. Yes it causes a CEL, but you can get past the CEL for 20 dollars from www.boxer4racing.com .
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Old 08-25-2003, 11:04 AM   #9
Imprezive2002
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ive been catless for the past 3 weeks i think you guys shouldnt do it im puting mine back on specially if you have a light color car white or silver.. smell kinda gets to you along with the loudness. and might discolor the back bumper depending on how its tilted or put on just my opinion `Nick
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Old 08-25-2003, 12:04 PM   #10
Supapooh
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No cat? No resonator? got fireballs?? We are currently working on manufacturing bolt in "test pipes" along with a high flow cat. Things should get rather interesting. Right now I am running borla header, random tec cat, stromung mid-pipe and a blitz nurspec rear section. It is very loud. I can't wait to hear it with the test pipe
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Old 08-25-2003, 06:42 PM   #11
That Guy
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So what do you guys running catless do with the O2 sensors? Do you remove them completely? Are they just dangling there or have you got 'em screwed in the cat section piping anyway?

I'm curious too at the smog shop how you can pass even without a CEL or a with a CEL fix. Every car I've seen running catless you can smell from blocks away. "You runnin' a little rich there...?"
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Old 08-26-2003, 01:01 AM   #12
Zen
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Default

yeah, what do you guys do with your o2 sensors.. would it matter much?
anyone running catless with scoobysport catback? if so,,, how does it sound? does it get even crazier than it already is by itself?
also.. are any of you guys running 2.5"? or is it unnecessary to run such big piping on a non built n/a engine?
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Old 08-26-2003, 07:30 AM   #13
GQ
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Does running without a cat cause the exhaust to belch flames?
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Old 08-26-2003, 11:53 AM   #14
MY99 2.5GT
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It causes the car to backfire significantly more and I'm sure a flame or two can be seen at night.

You will still need to run the front O2 sensor to regulate the fuel air mixture and to detect missfires. The rear O2 is only there to tell the Ecu if the cat is functioning properly. Obviously it won't be once you remove it so you may as well unplug your rear O2 and keep it in the glove box or tool box for when you need to go pass emmissions.

Last edited by MY99 2.5GT; 08-26-2003 at 12:02 PM.
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Old 08-26-2003, 09:31 PM   #15
dynoguy
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where i live there is no al gore's to check our emissions. and the only time i seem to get a small back fire is between shifts some times when engine is cold and throttle slightly open. most likely do to o2 sensors on warm-up and rich start-up fuel map.

mike kasch
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Old 08-27-2003, 10:29 AM   #16
Imprezive2002
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actually both o2 sensors are there but still get the check engine light on cause of no cat.. but the place i had it custom done put them in some how they did a good job.. tommorrow im getting my hi-flo cat back on with kartboy hangers and a HKS hi-power exhaust i can't wait ill take pic or something when i get it back peaceeeeeeee Nick
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Old 08-28-2003, 04:13 PM   #17
MY99 2.5GT
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Did you guys that are running catless expereince a massive increase in exhaust sound level?
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Old 08-28-2003, 04:22 PM   #18
GQ
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I certainly did notice a massive increase in exhaust sound level once I installed a Stromung high flow cat in line with the Stromung exhaust.
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Old 08-29-2003, 01:22 AM   #19
Imprezive2002
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yea very noticeable hahaha
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Old 09-08-2003, 06:38 PM   #20
Zen
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Location: Toronto "spd frk"
Default

Anyone using MIL eliminators?
if so do you put your stock exhaust system back on? would using the MIL elim. totally mess up your rear O2 sensor so you couldnt really use it with the stock exhaust again?
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Old 09-08-2003, 11:52 PM   #21
EvasionOfTruth
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Quote:
Originally posted by Zen
Anyone using MIL eliminators?
if so do you put your stock exhaust system back on? would using the MIL elim. totally mess up your rear O2 sensor so you couldnt really use it with the stock exhaust again?
You can use it still. It's just fooling your ecu, cat or not it makes the ecu think there is a functioning cat. I'm not even using my rear O2 sensor anymore.
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Old 09-10-2003, 11:12 AM   #22
MY99 2.5GT
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I just put the straight pipe on and rarely get backfires and my CEL has come on once but has been off ever since that first day. Weird. I guess Mass Airflow cars regulate fuel much better then the newer MAP cars that run really rich. My friends 2000 RS with high flow cat backfires way more then my Mass Airflow does with straight pipe.

Brad
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