UEL Headers

[Jeikun]

Hey guys. Long time no see.

I've got a question about UEL headers in my car. It's an '08 Impreza 2.5i, entirely stock still. I want to put on UEL headers and modify the exhaust to make it sound burly even though it's really not...

Based on the research I've done, typical headers wont fit on my car and most major manufacturers aren't making them for my model. How difficult is it to modify ordered headers to fit onto my car?

Jake

[wrxkidid]

You know that those headers really wont help out with any power at all right???

[Evo Mike]

why?

[Kevin M]

Originally Posted by wrxkidid

You know that those headers really wont help out with any power at all right???

Yes, he knows, which is why he mentioned sound instead.

Originally Posted by Evo Mike

why?

It sounds better.

[Jeikun]

Thanks Kevin. That's pretty much it.

[sperry]

Wouldn't an axle-back setup be a cheaper/better option for making the car sound better?

[Jeikun]

Would it create the boxer rumble? I read on NASIOC that without the UELs since the stock 2.5i has equal length that it wont sound as good.

[wrxkidid]

And a lot cheaper...but i feel like the 08 rs has EL headers so he wouldn't get the boxer rumble which is what he is going for? I may be completely wrong though.

[bigrobwoot]

From what I've read, you need the catpipe from an 05 or earlier for the headers to fit, and the catback should fit, stock or aftermarket. Although, with the stock catback, you really can't tell much of a sound difference. Personally, I would (and did) get a trackpipe with the headers, but if you want to stay legal, I still have my stock catpipe somewhere. PM me if you want it for cheap.

[Jeikun]

PM sent.

[Evo Mike]

I was referring to why it wouldn't increase power at all.. are the pipes the same size or something?

[bigrobwoot]

Because it's going from the stock equal length headers to unequal length headers.

[Dean]

On a NA, I bet you will lose power with anything but EL headers. I'd start with a cheap cat back and see what you think.

[bigrobwoot]

Originally Posted by Dean

On a NA, I bet you will lose power with anything but EL headers. I'd start with a cheap cat back and see what you think.

"cheap catback" is kind of a relative term, since it is by far the most expensive bolt on for an NA. Also, I think he won't lose too much from switching to uel, since they will be aftermarket and therefore larger diameter than stock, I'm assuming. Then again, what the fuck do I know? LOL. I've never heard of anyone getting a before and after dyno on the 06+ NAs with UEL headers. That's my theory, maybe I'm completely wrong, which is totally possible

[Dean]

The Turbos all but requires UEL for different design reasons, heat, location, etc., but that does not make them optimal. In general, EL allow for the best flow and performance. That is probably why Subaru went that way on the NA in addition to it being cheap and easy.

I can't find a picture of the stock midpipe, but if it isn't too restrictive, an axle back might be all it would take to loud it up a bit. A quick google search didn't find any, but judging from the aftermarket cat backs, I would guess one could be fabbed for 2-300 bucks.

[bigrobwoot]

Originally Posted by Dean

The Turbos all but requires UEL for different design reasons, heat, location, etc., but that does not make them optimal. In general, EL allow for the best flow and performance. That is probably why Subaru went that way on the NA in addition to it being cheap and easy.

I can't find a picture of the stock midpipe, but if it isn't too restrictive, an axle back might be all it would take to loud it up a bit. A quick google search didn't find any, but judging from the aftermarket cat backs, I would guess one could be fabbed for 2-300 bucks.

I didn't think about the custom route. But if he plans on doing a full exhaust eventually, just an axleback would be a waste of money, since you usually get a bit of a discount buying the full catback. As far as I know, the Catback is the same as previous years, so aftermarket catbacks or axlebacks should be easy to find.

I agree that el is better than uel generally, but if the aftermarket uel is a bigger diameter than the stock el, couldn't it potentially flow almost as well? I think it could, that's all I'm saying.

[Dean]

Not disagreeing, I am not sure, just going from experience.

Subaru typically makes really good headers though. As far as I know, there are only a couple companies that actually claim to make more power on earlier NAs and then I believe only at high RPM at the expense of the low end.

The full cat backs look to be well over $500, that is why I suggested fabbing something. I only suggested skipping the mid as they are often not a restriction or much of a baffle relative to the cat and the axle back on older turbo models was a huge restriction. Summit also has a great selection of mandrel bent pipes, flanges and mufflers for cheap. one of the few benefits of Reno.

[bigrobwoot]

Haha I'm not too sure either, just parroting what I read on forums, and trying to apply some of my college learnin' lol

[sperry]

Larger diameter headers on N/A cars usually doesn't help for power unless the original headers are grossly undersized. Usually aftermarket headers on N/A cars make gains by tuning the length to properly match the speed of sound in the tube coupled with the exhaust pulse spacing to allow the sound waves to help extract more exhaust from the cylinders.

Frequently, if you go to a larger diameter header pipe, you do flow more which gives you some more top-end, but it's at the loss of low-end torque. I'd rather keep the low-end that I use everyday than gain a little horsepower that I would only use when wringing the car out to red-line. YMMV w/ the 2.5i though... I don't know how the 2.5L N/A motors react... but I would bet ideal performance would come with much longer primary pipes of stock diameter, and keeping the equal length. But that would sound crappy, and be hard to fit under the car.

If sound is the goal, some stock diameter UEL headers would probably work best. How hard is it to convert a pre-08 header-back exhaust to work on the 08s?

[wrxkidid]

Originally Posted by bigrobwoot

Haha I'm not too sure either, just parroting what I read on forums, and trying to apply some of my college learnin' lol

And I was under the impression that UNRs engineering school was decent.. just yankin your chain Robbie.

[bigrobwoot]

No one said UNR had a great engineering program, and I'm barely sliding by haha.

For real tho, if it was water, not air, I could do the math on it. They are similar, so the math would probably be similar, but I don't know the dimensions of any of the headers, I'm sure more engineering went into both designs than I could ever hope to be able to do, and I just don't wanna do it

[bigrobwoot]

Sperry: the new design on the 06+ NA imprezas would require the catpipe to be modified for it to work. Shortened and staggered more towards the center of the car, if I'm not mistaken. I'm pretty sure the new headers have short primaries that come out in the center of the car (equidistant from the doors) while the older ones were similar to WRX headers, except they stay flat instead of going up into the uppipe. Let me know if I can be more clear with that description.

[Jeikun]

One day we should meet up at the JCSU or the Overlook hahaha. Summer classes anyone?

I'm not quite sure what to do. I want to give my car more power but I dont want to end up losing low-end, so that means that larger headers are out of the question. My goal here is primarily sound, with power as a close second. I dont want a really loud sound, I'm just lookin to make it sound a little more burly. As burly as a n/a 2.5 can...

I'm not quite sure where to go next here. I've been seriously considering buying the catpipe from rob and then just kind of figuring out where to go from there. I guess what I'm trying to say (ask) is, and this is gonna make me sound nieve... but, on a budget, what would be the best way to make my car sound better while maintaining/increasing power output?

[wrxkidid]

Its a tough one to gauge. Have you looked around on nasioc or 25rs.com? Those sites have quite a few more members, which in turn gives you a lot more opinions and even some results from what people have tried, what works and what doesn't, ect.

That would be a place to look I would say. I mean the only way to know for sure is to try it and see what happens but I know your in college so money isn't really disposable haha.

[Dean]

Here is a thought. Take off the axle back and see what it sounds like. It will likely be louder than you want, but will give you a feel for what the tone and burliness of louder is. If it is acceptable but needs to be muffled, a straight through can of some shape muffler and some fab work will deliver for cheap.

You could also drop the mid pipe for kicks.

If you don't like the sound, you have to look for UEL options.