Welcome to the North American Subaru Impreza Owners Club Thursday May 28, 2015
Home Forums WikiNASIOC Products Store Modifications Upgrade Garage
NASIOC
Here you can view your subscribed threads, work with private messages and edit your profile and preferences Home Registration is free! Visit the NASIOC Store NASIOC Rules Search Find other members Frequently Asked Questions Calendar Archive NASIOC Upgrade Garage Logout
Go Back   NASIOC > NASIOC Technical > Normally Aspirated Powertrain

Welcome to NASIOC - The world's largest online community for Subaru enthusiasts!
Welcome to the NASIOC.com Subaru forum.

You are currently viewing our forum as a guest, which gives you limited access to view most discussions and access our other features. By joining our community, free of charge, you will have access to post topics, communicate privately with other members (PM), respond to polls, upload content and access many other special features. Registration is free, fast and simple, so please join our community today!

If you have any problems with the registration process or your account login, please contact us.
* Registered users of the site do not see these ads.
Reply
 
Thread Tools Display Modes
Old 03-02-2008, 09:04 PM   #1
GrundleJuice
NASIOC Supporter
 
Member#: 165749
Join Date: Dec 2007
Chapter/Region: South East
Location: ლಠ益ಠ&
Default Random Single/Dual Line Cat's

What is the difference between the single and dual line high flow cats made by random tech? I talked to ultrarev today because im waiting on my damn cat STILL, and they mentioned something about the dual line being a better choice to avoid CEL's. but they already have a single line cat ready to ship so i want to know what the difference is and if i should wait another week or so and get a dual line? Any performance difference? Apparantly the dual line type is the OEM style. According to the specs there are 2 O2 sensor bungs on both types, so I dont think it has anything to do with that. I did a serach on here and found a couple mentions of a dual line cat in the N/A w/ aftermarket forced induction forum and nothing on google. Maybe the dual line is for a turbo application? Thanks for any help.
* Registered users of the site do not see these ads.
GrundleJuice is offline   Reply With Quote
Sponsored Links
* Registered users of the site do not see these ads.
Old 03-02-2008, 09:28 PM   #2
piker28
Scooby Guru
 
Member#: 22664
Join Date: Aug 2002
Location: north nj
Default

I doubt any perfomance differences this is a NA car to be honest. I take it little bit of tryin to be more legal since theres two cats in the stock pipe so two hfc replacement.

Also you do know you need the headers and catback to run a 98-05 catpipe?
piker28 is online now   Reply With Quote
Old 03-02-2008, 09:58 PM   #3
GrundleJuice
NASIOC Supporter
 
Member#: 165749
Join Date: Dec 2007
Chapter/Region: South East
Location: ლಠ益ಠ&
Default

So you are saying that the dual line has two cats in line and the single just one? makes sense, the pics both show two chambers but i guess the pics don't mean anything on the retail website.

yeah, i have a stromung dual tip catback and TWE SS headers so im golden.. just waiting very very patiently on this damn HFC!!
GrundleJuice is offline   Reply With Quote
Old 03-02-2008, 11:21 PM   #4
EdHilario
Scooby Specialist
 
Member#: 137398
Join Date: Jan 2007
Chapter/Region: E. Canada
Location: Toronto
Vehicle:
2004 Impreza 2.5RS
Platinum Silver Metallic

Default

The dual in-line cat pipe will be quieter than the single cat pipe. I was thinking of getting the one with two just for emissions sake but I think the one would be enough.
EdHilario is offline   Reply With Quote
Old 03-03-2008, 12:08 AM   #5
williaty
Scooby Guru
 
Member#: 71092
Join Date: Sep 2004
Chapter/Region: MWSOC
Location: Delaware County, Ohio
Vehicle:
2005 2.5RS Wagon
Regal Blue Pearl

Default

Taking a rough sampling of people's experiences here and on rs25, it seems that the "double-bubble" RT is MUCH less likely to throw a 420 and MUCH more easily made happy if the ECU does get cranky.

Obviously, there's going to be a difference in sound, but who knows which way.
williaty is offline   Reply With Quote
Old 03-03-2008, 02:38 AM   #6
rougeben83
Scooby Guru
 
Member#: 115154
Join Date: May 2006
Chapter/Region: MWSOC
Location: NYC
Vehicle:
2005 Outback XT
White on grey

Default

More cats usually mean less rasp in the exhaust...it's like a resonator. I don't think there's that much of a difference in performance between the two. Today's cats don't take away as much HP as many people are led to believe.

The dual cat was made by RT in response to people still getting CEL's even with the single cat. If your state doesn't have emissions testing and/or you don't mind taking the slight extra risk of getting a CEL, the single would be fine (esp considering it's cheaper than the dual cat IIRC).
rougeben83 is offline   Reply With Quote
Old 03-03-2008, 10:51 AM   #7
Flaps
Scooby Newbie
 
Member#: 105490
Join Date: Jan 2006
Chapter/Region: VIC
Location: Langley, BC
Vehicle:
2005 Impreza 2.5RS
PSM 2.5L of N/A fury :-(

Default

I put on the Random Tech dual cat a month or so ago. This is on a 2005 RS with TWE headers and Stromung everything else. I haven't driven much on the highway, so I don't know if I'll get a CEL doing that like I did with the Stromung cat.

With this new setup I don't have a spacer or anything on the rear O2 sensor, and I did get a brief CEL a couple of times when driving at around 75KM/h for a while. Reset the ECU and it's been fine for a few weeks now though. Overall I think it's better, but I might try a spacer on the rear O2 in the future.
Flaps is offline   Reply With Quote
Old 03-04-2008, 08:35 PM   #8
GrundleJuice
NASIOC Supporter
 
Member#: 165749
Join Date: Dec 2007
Chapter/Region: South East
Location: ლಠ益ಠ&
Default

Quote:
Originally Posted by Flaps View Post
I put on the Random Tech dual cat a month or so ago. This is on a 2005 RS with TWE headers and Stromung everything else. I haven't driven much on the highway, so I don't know if I'll get a CEL doing that like I did with the Stromung cat.

With this new setup I don't have a spacer or anything on the rear O2 sensor, and I did get a brief CEL a couple of times when driving at around 75KM/h for a while. Reset the ECU and it's been fine for a few weeks now though. Overall I think it's better, but I might try a spacer on the rear O2 in the future.
****! I just canceled the whole order cuz the place i ordered from was doing something fishy with my credit card and my CC bank called and asked me if/why my CC was being used so much within minutes. Sounded like some scam deal and the merchant (UltraRev) wouldn't help me out with it. anyway i went back to Boxer$ cuz they are cool and got the stromung cat and i have TWE headers so guess i should plan on a CEL. oh well, something else to mess with. better than being bored i guess.

Quote:
Originally Posted by williaty View Post
Taking a rough sampling of people's experiences here and on rs25, it seems that the "double-bubble" RT is MUCH less likely to throw a 420 and MUCH more easily made happy if the ECU does get cranky.

Obviously, there's going to be a difference in sound, but who knows which way.
Yeah, thats what the merchants website said in a nutshell. but i went with the stromung cat after all and boxer4 has my cat on the way and is making me happy.

thanks for the info, guys.
GrundleJuice is offline   Reply With Quote
Old 03-05-2008, 12:24 AM   #9
Flaps
Scooby Newbie
 
Member#: 105490
Join Date: Jan 2006
Chapter/Region: VIC
Location: Langley, BC
Vehicle:
2005 Impreza 2.5RS
PSM 2.5L of N/A fury :-(

Default

Quote:
Originally Posted by RaceFaceXC View Post
****! I just canceled the whole order cuz the place i ordered from was doing something fishy with my credit card and my CC bank called and asked me if/why my CC was being used so much within minutes. Sounded like some scam deal and the merchant (UltraRev) wouldn't help me out with it. anyway i went back to Boxer$ cuz they are cool and got the stromung cat and i have TWE headers so guess i should plan on a CEL. oh well, something else to mess with. better than being bored i guess.



Yeah, thats what the merchants website said in a nutshell. but i went with the stromung cat after all and boxer4 has my cat on the way and is making me happy.

thanks for the info, guys.
Well my Stromung cat was fine around town, but driving over 90km/h for more than say 30 minutes would give me a CEL. It would go away on its own after driving around town for a week or so, but it was still annoying to see it.

I got my TWE headers ceramic coated recently, and with the Random Tech dual cat, I'm hoping the CEL will stay away more now. I haven't driven enough on the hiway yet to tell.
Flaps is offline   Reply With Quote
Old 03-05-2008, 01:44 AM   #10
EdHilario
Scooby Specialist
 
Member#: 137398
Join Date: Jan 2007
Chapter/Region: E. Canada
Location: Toronto
Vehicle:
2004 Impreza 2.5RS
Platinum Silver Metallic

Default

RaceFace, is UltraRev not a trustworthy website with CC?
EdHilario is offline   Reply With Quote
Old 03-05-2008, 07:05 PM   #11
GrundleJuice
NASIOC Supporter
 
Member#: 165749
Join Date: Dec 2007
Chapter/Region: South East
Location: ლಠ益ಠ&
Default

i dunno, i hesitate to say that UltraRev.com is not trustworthy, but it sure isnt working well... The guy I talked to on the phone said that they dont have any problems with PayPal payments, implying that they have had problems with their checkout system. Anyway, it was just way too much BS and lack of desire to resolve my issue (took 5 days). My CC provider didnt do anything to help, either, which didn't help things at all! Just be cautious I suppose.
GrundleJuice is offline   Reply With Quote
Old 03-06-2008, 03:57 PM   #12
PA-Outback2000
Scooby Specialist
 
Member#: 161832
Join Date: Oct 2007
Chapter/Region: Tri-State
Location: PA
Vehicle:
2000 Outback Limited
Black

Default

EL headers have a slightly better chance of giving a CEL over UEL headers. stromung's HFC also has slightly better chance of throwing a CEL over the random tech one. in general, single cats have a better chance of throing a CEL over the dual cats. i have been doing research with companies and other forums and have come to discover that borla header, randon dual HFC, and stromung/ any other catback seems to be a very popular setup. this setup has the least chance of throwing a CEL, but if it does, there are fixes/spacers for the 02 sensor that lessen the chance of throwing a CEL.
PA-Outback2000 is offline   Reply With Quote
Old 03-06-2008, 08:01 PM   #13
GrundleJuice
NASIOC Supporter
 
Member#: 165749
Join Date: Dec 2007
Chapter/Region: South East
Location: ლಠ益ಠ&
Default

yeah, ill probably try a O2 spacer before I try a new cat. I would like to avoid a CEL at all times if possible, but if the stromung cat causes a CEL often and the Random dual line "double bubble" cuts the CEL frequency down significantly, id ba happy with getting that. Ill post some CEL results after i install the exhaust and get a tank of gas on it and then some longer term stuff with the TWE SS 4-2-1 headers, stromung HFC, stromung catback (dual tip). ill do dome logging, too, see what changes are occurring and then use them to tune if i can gain anything besides the bolt on gains. Anyone know if any tuning or what type of tuning one can expect to achieve more gains from after doing an exhaust setup like this one? I should get a better cylinder charge with the tuned EL setup, but i dont understand what changes in ECU would take advantage of that. thanks for any ideas/suggestions.
GrundleJuice is offline   Reply With Quote
Old 03-06-2008, 10:31 PM   #14
EdHilario
Scooby Specialist
 
Member#: 137398
Join Date: Jan 2007
Chapter/Region: E. Canada
Location: Toronto
Vehicle:
2004 Impreza 2.5RS
Platinum Silver Metallic

Default

PA-Outback, how come EL headers are more likely to give a CEL than a UEL header?
EdHilario is offline   Reply With Quote
Old 03-07-2008, 05:47 AM   #15
PA-Outback2000
Scooby Specialist
 
Member#: 161832
Join Date: Oct 2007
Chapter/Region: Tri-State
Location: PA
Vehicle:
2000 Outback Limited
Black

Default

racefacexc, what do u mean by "cylinder charge?" the only tuning possible, but not really needed is a new engine management unit or piggyback unit. just using bolt-ons doesn't "require" tuning. for the most part, the stock ECU compensates for the changes.

edhilario, the EL flow a larger volume of air through the system and will throw off the programmed tollerances in the computer. if using the borlas, it just smoothes out the flow compared to the stock ones. i haven't heard/read anything if the O2 spacer solves the problem in this case. i will try to find out and post back.
PA-Outback2000 is offline   Reply With Quote
Old 03-07-2008, 04:29 PM   #16
Storm
Scooby Guru
 
Member#: 5218
Join Date: Mar 2001
Chapter/Region: MWSOC
Location: SAUL'S Motorsports
Vehicle:
96L Most Over-
Developed Beater

Default

Check this out......Just saw it linked in a thread over on RS25.com. Looks very promising and not uber-expensive......
http://store.summitracing.com/partde...5&autoview=sku

Jay Storm
Storm is offline   Reply With Quote
Old 03-07-2008, 04:50 PM   #17
williaty
Scooby Guru
 
Member#: 71092
Join Date: Sep 2004
Chapter/Region: MWSOC
Location: Delaware County, Ohio
Vehicle:
2005 2.5RS Wagon
Regal Blue Pearl

Default

So that's an integrated header and HFC?
williaty is offline   Reply With Quote
Old 03-07-2008, 06:02 PM   #18
GrundleJuice
NASIOC Supporter
 
Member#: 165749
Join Date: Dec 2007
Chapter/Region: South East
Location: ლಠ益ಠ&
Default

Quote:
Originally Posted by PA-Outback2000 View Post
racefacexc, what do u mean by "cylinder charge?" the only tuning possible, but not really needed is a new engine management unit or piggyback unit. just using bolt-ons doesn't "require" tuning. for the most part, the stock ECU compensates for the changes.

edhilario, the EL flow a larger volume of air through the system and will throw off the programmed tollerances in the computer. if using the borlas, it just smoothes out the flow compared to the stock ones. i haven't heard/read anything if the O2 spacer solves the problem in this case. i will try to find out and post back.
Cylinder charge means more complete filling of the cylinder with fuel/air mixture on the intake stroke. EL headers that are tuned length do a better job of scavenging the spent exhaust gases from the cylinder on the exhaust stroke and therefor also make the intake stroke more efficient. The only tuning possible is not just replacement ECU or piggyback, there is also OpenSource which is what I am currently using (Enginuity/RomRaider) but dont know what ECU changes will benefit in terms of power after putting on that exhaust system. some bolt-ons do require tuning to get the most out of the bolt-on's potential. (CAI, SRI are examples that benefit greatly from tuning) Thanks for your opinion, though. BTW, your reply to EdHiliario complete contrdicts your reply to me about tuning and UEL's do anything but smooth out exhaust flow. The rumble created by UEL's is because of staggering the exhaust pulses by making some cylinders exhaust pulses travel further than others so they dont merge nicely at the collector but instead are staggered and interrupted. Hmmm... I think you are incorrect about why EL and UEL headers may be more/less likely to throw a CEL. just my opinion.
GrundleJuice is offline   Reply With Quote
Old 03-07-2008, 07:29 PM   #19
EdHilario
Scooby Specialist
 
Member#: 137398
Join Date: Jan 2007
Chapter/Region: E. Canada
Location: Toronto
Vehicle:
2004 Impreza 2.5RS
Platinum Silver Metallic

Default

Quote:
Originally Posted by williaty View Post
So that's an integrated header and HFC?
That's what it looks like in the picture but the prod. desc. says that it's only a cat.
EdHilario is offline   Reply With Quote
Old 03-07-2008, 09:10 PM   #20
PA-Outback2000
Scooby Specialist
 
Member#: 161832
Join Date: Oct 2007
Chapter/Region: Tri-State
Location: PA
Vehicle:
2000 Outback Limited
Black

Default

racefacefx...good point, but don't think we were talking about pulses here. i may have read your "tuning" part wrong. i may be wrong in how i am correcting myself, but i meant to say that EL headers are what they say, EL. this means that the lengthened side of the header allows more air to flow through the system, compared to the "staggered" side of UEL. this makes for a slightly better chance for a CEL. if this doesn't help, maybe rephrase what u r asking.
PA-Outback2000 is offline   Reply With Quote
Old 03-07-2008, 10:03 PM   #21
williaty
Scooby Guru
 
Member#: 71092
Join Date: Sep 2004
Chapter/Region: MWSOC
Location: Delaware County, Ohio
Vehicle:
2005 2.5RS Wagon
Regal Blue Pearl

Default

Quote:
Originally Posted by PA-Outback2000 View Post
racefacefx...good point, but don't think we were talking about pulses here. i may have read your "tuning" part wrong. i may be wrong in how i am correcting myself, but i meant to say that EL headers are what they say, EL. this means that the lengthened side of the header allows more air to flow through the system, compared to the "staggered" side of UEL. this makes for a slightly better chance for a CEL. if this doesn't help, maybe rephrase what u r asking.
What you just said isn't strictly correct.

An EL or UEL header can be designed to flow exactly the same amount as each other, neither design has an inherent flow advantage.

The EL headers are more efficient at one aspect of scavenging (resonant tuning). This is how they get more air into the cylinder.

If there is a correlation between EL vs UEL and CELs, and I certainly haven't noticed one, then the most likely cause is that most of the EL designs are "more serious". The Borla knockoffs don't really flow much more than stock because they're not a very good design for flow (of which being UEL is only a small part). Most of the EL designs are from companies chasing that last 10hp, which results in much better designs (of which EL is only a small part) and therefore much more flow.
williaty is offline   Reply With Quote
Old 03-07-2008, 10:16 PM   #22
GrundleJuice
NASIOC Supporter
 
Member#: 165749
Join Date: Dec 2007
Chapter/Region: South East
Location: ლಠ益ಠ&
Default

I wonder if TWE would make a set of real nice UEL's with Burns collector(s) and get that sweet sound with all the performance, too. it's only $$$$!
GrundleJuice is offline   Reply With Quote
Old 03-07-2008, 11:04 PM   #23
williaty
Scooby Guru
 
Member#: 71092
Join Date: Sep 2004
Chapter/Region: MWSOC
Location: Delaware County, Ohio
Vehicle:
2005 2.5RS Wagon
Regal Blue Pearl

Default

It'd have less flow than an EL design, but I'm sure it would nicely kick borla ass.
williaty is offline   Reply With Quote
Old 03-08-2008, 03:13 AM   #24
EdHilario
Scooby Specialist
 
Member#: 137398
Join Date: Jan 2007
Chapter/Region: E. Canada
Location: Toronto
Vehicle:
2004 Impreza 2.5RS
Platinum Silver Metallic

Default

Damnit TWE, go down in price like 50% lol
EdHilario is offline   Reply With Quote
Old 03-08-2008, 09:52 AM   #25
GrundleJuice
NASIOC Supporter
 
Member#: 165749
Join Date: Dec 2007
Chapter/Region: South East
Location: ლಠ益ಠ&
Default

yeah.. i need to find me a sugar mama.
GrundleJuice is offline   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Random Single wheel and tire.. scottronics01 Wheels/Tires 0 11-17-2009 04:07 PM
Borla Single Port Headers & Random Tech Cat JayGold 1993 - 2001 Impreza Specific Parts 5 02-22-2008 12:14 PM
Maddad Whisper Single/Dual tofushopguy Bay Area Impreza Club Forum -- BAIC 2 01-20-2008 04:25 AM
Random Tech duel line CAT?? Brindor2.5 Normally Aspirated Powertrain 0 05-30-2007 06:15 PM
EJ22 Impreza L single/dual port heads SiNzz Normally Aspirated Powertrain 22 07-21-2006 12:20 PM


All times are GMT -4. The time now is 04:26 PM.


Powered by vBulletin® Version 3.7.0
Copyright ©2000 - 2015, Jelsoft Enterprises Ltd.
Powered by Searchlight © 2015 Axivo Inc.
Copyright ©1999 - 2015, North American Subaru Impreza Owners Club, Inc.