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Another 2.5i UEL thread... Couple Quick Questions


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I know this modification has been covered hundreds of times between this great forum and others; however, I have still got a few questions that are kind of hard to answer myself with all of uel header mod photos taken from different view points. First off, I'm going to be attempting this on my pzev 2008 legacy 2.5i se, 5spd, with full stock exhaust currently. I have been contemplating whether to go the route of a pre-2005 (rs) exhaust setup, 2.5rs borla replica with the pre-05 cat/midpipe; or the route of hacking up a ebay wrx header to bolt up to my stock 3bolt midpipe. I know many of you will recommend using a stock cast iron lgt/wrx manifold; however I don't have any experience with welding cast iron and have heard its pretty tough to do right? One of my main question right now is, if i decide to use a 2.5rs header and stock 2.5rs midpipe, will this setup, (mostly concerned with the midpipe), bolt up directly to my stock catback?? I know the 2.5rs midpipe exits somewheres in the middle, just not sure if its even close to my 2.5i catback location. I know I can go look under my car myself, just wondering if anyone has experience with this? Im pretty sure this setup bolts directly to the impreza 2.5i stock cbe, not sure the difference between impreza 2.5i cbe vs the legacy's? Second question, because I dont have the skill to weld cast iron, will there be enough room to cut back into the (ebay) wrx header, either the one piece ((flex up pipe) or two piece, not sure if that matters) to make it fit without modifying the 4 way collector, if that makes sense, hard to explain it? I believe there is enough room to just cut the single exit pipe of the header to make it fit my stock cat?, which i do not really want to modify. These are pretty much what I have narrowed my choices down too. Really just looking for the desirable subie rumble my car is missing. Any information from somebody that has done this would be great! Ive pm'd a couple of you for advice and got some great feedback already. Thanks again -Aaron (newish to the forum) [* I have been researching this now for a few weeks and understand most of it so don't hold back on the terms, I should understand what your saying.]
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Im going to step in :lol:

 

http://legacygt.com/forums/showthread.php/2-5i-header-tail-pipe-165409.html?&highlight=2.5i+header

 

OR

 

http://legacygt.com/forums/showthread.php/borla-header-install-06-2-5i-60348.html?t=60348&highlight=2.5i+header

 

Or even our Russian brothers method is great

 

http://www.drive2.ru/cars/subaru/legacy/legacy_5th_generation/rb-man/journal/288230376151863731/

 

OR buy these from a forum member

 

http://legacygt.com/forums/showthread.php/ct-rallisport-racing-uel-header-214096.html?t=214096&highlight=UEL

 

 

 

Quick answers:

 

The pre 05 will not bolt up to your stock CBE, its too short and clocked differently.

The Russian method has been performed on a members 2.5i on these forums user name desellers message him. No cutting or welding cast steel :)

The Borla type headers will melt your PS lines (trust me and MS PRO)

The Borla type headers will result in a CEL.

I would stay away form a cheap SUS304 WRX eBay header.

No difference in the LGT or 2.5i CBE

PZEV is a non-issue

The RS style layout would require two extensions for the O2 sensors

 

The easiest method is the Rallisport bolt on header

The most difficult is the RS style

The most frustrating is the LGT/WRX manifold style b/c no one wants to handle cast steel but is the most compact.

 

Read those links let us know if any catches your eye we can go from there :)

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How difficult is mig welding cast iron for somebody that knows how to weld? any experience?

 

Make your cut, heat the cast part up evenly, tack on the steel part, heat evenly then weld it as if you were welding 1/4" plate steel. Cool it slowly :redface:

 

Check out that Russian link however there is no angle guess work involved and you keep the OEM turbo manifold intact. All you would need is two bolt flange and some 2.25" bends which you might have laying around or can pickup for cheap.

 

http://d.a.d-cd.net/4acc288s-480.jpg

http://g.a.d-cd.net/7acc288s-480.jpg

http://b.a.d-cd.net/facc288s-480.jpg

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I know you said avoid the ebay wrx/lgt headers, which is understandable, haha. However, theoretically, do you think that there is enough pipe (on the ebay header) to cut off after the collector to fit in onto my car, with out messing around with the 4-1 collector. In other words, how many inches approximately need to be cut off the castiron manifold to make it fit. I guess that would be the best way to see? I would love to see the ebay header be able to be modded easily to fit my stock cat. Not sure if there would be more room to chop up a one piece or the shorter two piece header. I have some doubts as I have never seen this specific way done to a 2.5i??
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I was afraid you were going to say that, I've had my own suspicions that this was the reason this exact setup has not been done really, at least that I've come across. My only other idea would be to use the ebay header with the flexible up pipe piece attached, those seem to offer more room after the collector?
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I was afraid you were going to say that, I've had my own suspicions that this was the reason this exact setup has not been done really, at least that I've come across. My only other idea would be to use the ebay header with the flexible up pipe piece attached, those seem to offer more room after the collector?

 

 

Well if you can do all the fab work on top of buying a based header for under $550 I would just but the used Rallisport headers :redface: bolt on/bolt off in minutes, compact and solid built in the USA!

 

 

 

Another and the main reason I wouldnt go the eBay RS style UEL is the thin walls of the primaries emit a sewing machine noise which is annoying(transmits the valve train sounds)

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Don't quote me on it but I believe that is the common practice for both of the header mods (both "2.5rs style" and lgt/wrx manifold). Gee-otto and other members who have completed this modification can give you a more in depth /precise answer. I have been told that the second factory cat is enough to keep the CEL away. I also know that AFR sensor must be relocated, which I believe is the sensor/bung welded into the pipe right after the collector (shown in pictures in other threads)
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i know the OEM manifold which i picked up last week has the first o2 bung in it already. i just wasnt sure of the second cat part

 

Two ways around that: relocated to the second stock cat or tune out the downstream sniffer.

 

THe downstream does nothing more that sniff and tell the ECU the cat is working.

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