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Old 11-22-2006, 02:12 PM   #1
Sir-Knight
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Default EL vs UEL headers and exhuast questions 06-07 2.5i

Okay, I'm doing some searching and reading, and there's not a whole lot in terms of parts for my car since it's new. But I do have some questions on parts that are out there for older cars. I'm pretty much a noob at mechanics and car modding, so bear with me as I'm attempting to educate myself and rise above the opinion, speculation and rumors. I need cold hard facts. If you don't have proof or reference, please don't clutter this thread. Thanks.


This is what I understand correct me if I am wrong:

an UEL header (Unequal length) will create the boxer growl by changing the timing in which the exhaust notes enter the cat to give it that staggered sound.

While creating this sound, an UEL will also lower the total power generated. The question here is: How much power does the UEL lose if any, compared to stock? Please provide proof, not conjecture or opinion.


A EL header (equal length) will not create a boxer growl, however power gains range from 5-10 hp. BUT my research from a few threads indicate that the boxer growl can be brought to life by "a good resonator" in the midpipe.

Are all resonators created equal? Is there a specific one I should be going after?

Also, apparently there was a change from 05 to 06 (and most likely 07) in the oil pan, so most headers made for those cars will not fit the 06-07. My research has uncovered a couple that do fit. Who has proof of the model and fit? Ebay parts do not apply here unless they are proven to be as effective in powergains and application as OEM or Aftermarket manufacturer parts.


In terms of a CATback, I can find any 06,07 WRX or STI catback and lengthen the midpipe, HOWEVER, stock exhaust is 2.25" while WRX and STI are 2.5-3"? Widening the pipe will cause loss of backpressure and therefore power, correct?

An 06,07 AXLEback from a WRX or STI will fit a 2.5i, provided that the flange (at the end of the midpipe?) is cut and rotated to fit, correct?
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Old 11-22-2006, 02:25 PM   #2
chrisarella
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I haven't read anything ever that would suggest that there were any gains going from an unequal to an equal length header. I'd love to see an undisputible fact posted. An undisputible fact would be a dyno graph on the same car, same dyno, same day, same atmospheric condtions.

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Old 11-22-2006, 02:47 PM   #3
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I have an 06 2.5i wagon with an 06 WRX catback, lengthened, and while I don't have any before & after dyno graphs I would say there was no loss of power anywhere in the RPM range. I'm also not going to claim any gains, but it does sound better than stock, and for a total of $125 a good deal.

There are several other posts dealing with the "06+ oil pan / Borla header" question, follow those as 2 of the guys are planning on actual test fittings.

No need to cut/flip the flange on the 06+, WRX/STI axle backs bolt right up, stock or aftermarket.

I believe RalliTek has a dyno of a before & after of the same car/day stock VS the RalliTek El header. And I believe there are several other people who have posted there gains from EL headers, Cobb may but the new site isn't complete. Also some of the power gain in the 06 2.5i(from 168 in 05 to 173 in 06) was from the switch to the EL header / manifold design, I doubt Subaru changed because the EL design gave less power.
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Old 11-22-2006, 03:40 PM   #4
Sir-Knight
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Quote:
Originally Posted by chrisarella View Post
I haven't read anything ever that would suggest that there were any gains going from an unequal to an equal length header. I'd love to see an undisputible fact posted. An undisputible fact would be a dyno graph on the same car, same dyno, same day, same atmospheric condtions.

Exactly my point... lots of opinion and conjecture flying around here when I'm looking for solid proof I'm sure there's a ton of people out there with 06-07 2.5is thinking and asking the same thing as me.

Quote:
Originally Posted by SubaDuba420
There are several other posts dealing with the "06+ oil pan / Borla header" question, follow those as 2 of the guys are planning on actual test fittings.
Yeah I've been keeping my eye on those as well, I'm not in a huge hurry since mods like these won't be coming near my car for at least a year or two, but when the wheels get grinding upstairs, they want some answers.
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Old 11-23-2006, 06:50 AM   #5
X4 SRT
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http://us.st11.yimg.com/us.st.yimg.c...5_1925_1755276

You guys that are asking these questions now days really need to start searching. The comparison between el an uel headers has been giong on for a very long time now. Dyno plots prove over and over again that gains with el headers are far better than those of uel design. Just look at the link I provided of the rallitek headers. They have a peak hp gain of about 13whp, and a paek tq gain of about 8wtq. Not bad. However peak numbers do not tell the whole story of how well this header improves on power. You have to look at the entire power band, and if you do, you will see that there are spots where the el header is making 20whp more than stock, and almost 25wtq more than stock. Those are not gains to be laughed at.

Heres some more links that cover the difference in gains of el vs uel.

http://forums.nasioc.com/forums/show...bb+header+dyno
http://forums.nasioc.com/forums/show...bb+header+dyno
http://forums.nasioc.com/forums/show...bb+header+dyno
http://forums.nasioc.com/forums/show...bb+header+dyno
http://www.techworkseng.com/News/Rel...adynotest.html
Those are just a few that I was able to find.

Also, I've said it before, and I'll say it again. If you are the owner of an 06+ N/A Impreza, and you replace the stock el header with an uel borla or borla replica you are an idiot. Plan and simple. If you can't figure out why after all the threads I've posted, then you will never get it.

Last edited by X4 SRT; 11-23-2006 at 07:50 AM.
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Old 11-23-2006, 08:51 AM   #6
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Quote:
Originally Posted by SubaDuba420 View Post
I believe RalliTek has a dyno of a before & after of the same car/day stock VS the RalliTek El header. And I believe there are several other people who have posted there gains from EL headers, Cobb may but the new site isn't complete. Also some of the power gain in the 06 2.5i(from 168 in 05 to 173 in 06) was from the switch to the EL header / manifold design, I doubt Subaru changed because the EL design gave less power.
I thought the extra power was from the addition of AVLS and not the header?
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Old 11-23-2006, 09:12 AM   #7
Sir-Knight
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Quote:
Originally Posted by X4 SRT View Post
http://us.st11.yimg.com/us.st.yimg.c...5_1925_1755276

You guys that are asking these questions now days really need to start searching. The comparison between el an uel headers has been giong on for a very long time now.
Are you accusing me of NOT searching? I've been going up and down the boards for a month now, searching on specific and not so specific threads. Does that mean ALL of my questions have answers or that I was able to 100% find EVERYTHING?


Quote:
Also, I've said it before, and I'll say it again. If you are the owner of an 06+ N/A Impreza, and you replace the stock el header with an uel borla or borla replica you are an idiot. Plan and simple. If you can't figure out why after all the threads I've posted, then you will never get it.
I didn't ask your opinion on whether or not it was a smart thing to do. I asked what were the differences should EITHER of them be applied. I asked some perfectly legitimate answers, all you needed to do was provide links to threads, not whether or not it was a smart or dumb thing to do. I'm looking for information, not your opinion on the wisdom of choosing either solution.

But thankyou anyways for your effort in helping me locate the threads. The information will be useful in my research and desicion making.
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Old 11-24-2006, 06:55 PM   #8
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Tech Works has a dyno comparison of stock vs. Borla vs. Equal length. I have had their EL header on my car for about two years now. It gained power everywhere and still sounds like a boxer, just a very well tuned boxer, not a Harley like the Borla sounds. I don't use a resonator in my cat-back.
www.techworkseng.com
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Old 11-24-2006, 08:08 PM   #9
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ok so let me see here..

1- you are asking to compare with the 06/07 stock unequal length? i guess i have no cold hard facts like you want (but ya know best most can do) is that you would not lose that much, from eyesight the header design is nothing that great, so just swapping it to the borlas shouldnt be anything drastic

2- i have not seen this to be true, resonators help to get rid of the raspyness in the exhaust, what little rumble there might be, yes it could help bring it out.. but again will only be at low rpms

3- nothing wrong with certain ebay stuff, i have ebay headers and they are better than the real deal. But to your question rallitek/obx equal length headers will fit your car.. cobb should be the same design so should be no reason they wil not work (but they cost a crapload)

4-last time i looked the stock exhaust is under 2", but that could have changed in 06. yes any wrx/sti catback would fit with a longer midpipe, a huge piped exhaust will kill torque while give minimal up top gains

5- from what many have done, a sti/wrx axleback will fit your car with 0 modification, but this is just the axleback not full catback without that lengthing you said

we were discussing the headers in another thread and me or another guy where gonna mess with a friends car and stick the borlas on em to see if it works, but who knows.. id reommend either try it or find a friend with some spare stuff aorund
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Old 11-24-2006, 08:11 PM   #10
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Quote:
Originally Posted by Sir-Knight View Post

I didn't ask your opinion on whether or not it was a smart thing to do. I asked what were the differences should EITHER of them be applied. I asked some perfectly legitimate answers, all you needed to do was provide links to threads, not whether or not it was a smart or dumb thing to do. I'm looking for information, not your opinion on the wisdom of choosing either solution.

But thankyou anyways for your effort in helping me locate the threads. The information will be useful in my research and desicion making.

if you don't want opinions.. why are you posting on a forum?! If you expect people to just give you all the facts you want at the drop of a hat like they are your nasioc servants without being able to share their personal thoughts and experiences.. then you are out of line man! the opinions should not be badgering or irrelevant.. but people have the right to give them.. most of the time in life things are based on opinion and speculation anyways.. there are a lot of very knowledgeable people on here who give very educated opinions based on your questions.. In my situations over the past 1.5 years.. many of those educated opinions were spot on and worked out very well.. I have learned a ton on here in the past year and if you quit trying to be tough guy you will too
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