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Old 03-01-2013, 12:40 PM   #76
MjSub2.0
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Any updates here?
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Old 03-01-2013, 02:55 PM   #77
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Yeah, I'll update later tonight...
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Old 03-02-2013, 03:47 PM   #78
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Now that I had a 4-1 header and full catback, I was curious if the factory cat pipe was the bottle neck in the system: (it is less than 2" going into the second cat and then 60mm going out. 60mm is right in between 2.25" and 2.5") So I threw this together:


Don't let that heat shielding fool you, it's like 1.9" piping under there. I replaced it with 2.25" piping and a HFC.


As I suspected, it made absolutely no difference below 4,500rpm but then gained
RPM
4250, +0
4500, +1
5750, +2
5000, +3
5250, +4
5500, +4
5750, +4
6000, +3
It should also be noted that I added a little tune at the same time, so I'm not sure how much of the tune was responsible for any gains.


Then just for fun I took my 4-1 header and hacked off the cat and add a venturi section:


The results were no gain in the bottom to mid and like 1hp or so in the upper end, but a god awful increase in loudness and rasp.


So I took that header and added back in the cat and modified it into a 4-2-1 header, because i didn't like the low rpm dip in torque the 4-1 made and although it made good power in the top end, it felt too "peaky" when driving.
Here's the results of the 4-2-1


Here's the hp gain over stock:
RPM
2000, +0
2250, +0
2500, +0
2750, +0
3000, +1
3250, +2
3500, +3
3750, +4
4000, +6
4250, +6
4500, +8
4750, +8
5000, +8
5250, +8
5500, +7
5750, +8
6000, +8
6250, +13
6500, +29

Now there was no loss in the bottom end, peak torque was raised only 200rpm to 4200 and when the stock hp rolled off at 6000, these kept climbing another 200rpm. Again, this was just an experiment, BUT its sill UEL it still has tons of rumble and it still makes power.

Last edited by blk6s; 03-04-2013 at 04:02 PM.
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Old 03-11-2013, 09:32 PM   #79
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^ I say you hit the jackpot with the 4-2-1 build.

As we all know, it is incredibly difficult to milk even 20+ hp increase out of the 2.0i or previous 2.5i even if we open up airflow AND give it a tune.
The fact that you got a steady increase for about +5 hp in normal driving conditions (approx 4k rpm) is already very impressive.
I just can't wait to hear the rumble :P

you sir, get a cookie
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Old 03-11-2013, 10:56 PM   #80
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Wonderful! Any projected time frame for a production ready header?
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Old 03-12-2013, 01:42 PM   #81
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How do you think to the 4-2-1 for the 2.5l benefit power wise compared to the 2.0l
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Old 03-16-2013, 08:53 PM   #82
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First of all, great numbers over the stock setup! My understanding is that performance often comes at some cost to fuel efficiency.. so naturally I'm curious, how much has ur avg mpg been affected from the tune and ur 4-2-1 header installation?
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Old 03-20-2013, 12:07 AM   #83
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Quote:
Originally Posted by Cranker625 View Post
^ I say you hit the jackpot with the 4-2-1 build.

As we all know, it is incredibly difficult to milk even 20+ hp increase out of the 2.0i or previous 2.5i even if we open up airflow AND give it a tune.
The fact that you got a steady increase for about +5 hp in normal driving conditions (approx 4k rpm) is already very impressive.
I just can't wait to hear the rumble :P

you sir, get a cookie
Quote:
Originally Posted by Wes_888 View Post
Wonderful! Any projected time frame for a production ready header?
Thank you. I'm going to test one or two more prototypes with smaller diameter primaries, to trade some of that top end gain for more bottom end. Peak hp numbers help sales, but I think most would be happier with a performance increase they can feel in normal stoplight to stoplight driving.

Unfortunately, I'm up to my eye balls in 2.5i uel header orders and am still in the process of developing a few axleback's for the 2.0i, so headers for the 2.0i may need to be put on the back burner. Good news is you can email me and order a "custom" header at any time, that way you can secure a spot on the waiting list (which is now approaching 3 months). A member on this forum has already placed a deposit on the prototype tested in my previous post.

Quote:
Originally Posted by Silver08Waggs View Post
How do you think to the 4-2-1 for the 2.5l benefit power wise compared to the 2.0l
The factory header on the 2.5i is a very good design and much harder to improve upon, especially when going from an efficient el design to a purposely uel design. The factory headers on the 2.0i aren't terrible, but certainly leave plenty of room for improvement.

Quote:
Originally Posted by tenaciousZ View Post
First of all, great numbers over the stock setup! My understanding is that performance often comes at some cost to fuel efficiency.. so naturally I'm curious, how much has ur avg mpg been affected from the tune and ur 4-2-1 header installation?
Hmm, good question. Actually, freeing up the exhaust should theoretically allow a small mpg increase, but the reality is that most people develop the lead foot syndrome after installing a performance part, especially one that creates a sexy rumble! I suffer from said syndrome. Plus, it's winter in MN, so letting the car idle for ten minutes before taking off each time isn't helping the cause.
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Old 03-20-2013, 05:37 PM   #84
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Quote:
Originally Posted by blk6s View Post
Thank you. I'm going to test one or two more prototypes with smaller diameter primaries, to trade some of that top end gain for more bottom end. Peak hp numbers help sales, but I think most would be happier with a performance increase they can feel in normal stoplight to stoplight driving.

Unfortunately, I'm up to my eye balls in 2.5i uel header orders and am still in the process of developing a few axleback's for the 2.0i, so headers for the 2.0i may need to be put on the back burner. Good news is you can email me and order a "custom" header at any time, that way you can secure a spot on the waiting list (which is now approaching 3 months). A member on this forum has already placed a deposit on the prototype tested in my previous post.



The factory header on the 2.5i is a very good design and much harder to improve upon, especially when going from an efficient el design to a purposely uel design. The factory headers on the 2.0i aren't terrible, but certainly leave plenty of room for improvement.



Hmm, good question. Actually, freeing up the exhaust should theoretically allow a small mpg increase, but the reality is that most people develop the lead foot syndrome after installing a performance part, especially one that creates a sexy rumble! I suffer from said syndrome. Plus, it's winter in MN, so letting the car idle for ten minutes before taking off each time isn't helping the cause.
That is amazing. Was this all done with a modified catback/exhaust or were only the headers replaced? I know this is still in prototype form, but what kind of warranty risks are we dealing with here using a modified header? Thanks!
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Old 03-24-2013, 08:46 PM   #85
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This is Part 2 of the exhaust, the 2nd CAT of the system, Just curios blk6s is this the magna flow CAT? Oh, did you ever get a High-Flow Resonator that resembles the OEM one? Any pics of it yet?
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Old 03-29-2013, 07:44 PM   #86
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News The Impreza 2.0i Header OMG!


Droooooling!
OMG!
Part 1 Done!
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Old 03-30-2013, 03:53 AM   #87
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Wow.. Could that be the much anticipated 4-2-1 UEL header with the Cerma chrome finish? I haven't found a production model on the Rallisport Racing website, is that one of the prototypes? Looks glorious!
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Old 03-30-2013, 03:18 PM   #88
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News The 2.0i Impreza with some bang!

Quote:
Originally Posted by tenaciousZ View Post
Wow.. Could that be the much anticipated 4-2-1 UEL header with the Cerma chrome finish? I haven't found a production model on the Rallisport Racing website, is that one of the prototypes? Looks glorious!
Yes it is! I bought the first prototype. I am working with the other sections of pipe with RalliSport Racing, I guess I am going to jump into part 3 (mid-pipe) of the exhaust since it's already made. Just needs to be finalized before getting the Cerma Krome Coating.


Last edited by ZURCALED12; 03-30-2013 at 03:19 PM. Reason: inserting picture
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Old 03-30-2013, 04:52 PM   #89
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Wow.. that looks really good. Cant wait till you get it installed! Post vids pls once you do!!
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Old 03-30-2013, 08:15 PM   #90
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Yes, pics and video of the full install please...=)
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Old 03-31-2013, 12:25 PM   #91
ZURCALED12
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This the WRX mid-pipe being modified to fit our 2.0i

It's not finished yet and it's not C.K. Coated either, so I will keep you posted.
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Old 03-31-2013, 01:38 PM   #92
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Nice! All this exhaust pioneering is exciting! What's the difference in pipe diameter from the stock to the WRX mid pipe?
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Old 03-31-2013, 10:25 PM   #93
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Angry The stock exhaust is very uneven!

Well, the stock exhaust is very uneven from 1.9" in some areas & up to on 2.5" wide in others. RalliSport Racing recommends a consistence 2.25" from header to muffler. Check out another video of the current exhaust on my Impreza. Not a good job at all!
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Old 04-01-2013, 12:58 AM   #94
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will this possibly fit on an 07 2.5i without throwing a cel
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Old 04-01-2013, 01:48 AM   #95
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Quote:
Originally Posted by Wes_888 View Post
Wow.. that looks really good. Cant wait till you get it installed! Post vids pls once you do!!
Quote:
Originally Posted by uspopo View Post
Yes, pics and video of the full install please...=)
Sorry, I made him sign a confidentiality agreement...

kidding of course
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Old 04-01-2013, 01:52 AM   #96
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Quote:
Originally Posted by hotwheelz8506 View Post
will this possibly fit on an 07 2.5i without throwing a cel
Headers made for the 2.0i definitely won't fit the 2.5i

I've sold over a hundred 2.5i headers though, so you are definitely hooked up there. Just visit RalliSportRacing.com
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Old 04-01-2013, 09:05 PM   #97
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I suck at making videos with a iPhone 4S, LoL!
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Old 04-03-2013, 03:51 AM   #98
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edit delete
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Old 04-04-2013, 04:11 PM   #99
ZURCALED12
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Talking OEM BOLTS/ SPRINGS/NUTS for Exhaust in Stainless Steel

44044AA010 Springs
44059AA010 Bolts
802008270 Nuts
Those are the part numbers for the OEM SUBARU parts for the mid-pipe hardware at the 2nd CAT pipe connection. I am guessing that getting these Cerma Krome Coated should make them last as long as the exhaust too. I have not found anyone that makes these in Stainless Steel.


This is the Dorman version of the exhaust kit no. 03114






Last edited by ZURCALED12; 04-04-2013 at 04:22 PM. Reason: Spelling correction
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Old 04-04-2013, 11:52 PM   #100
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Besides losing the boxer rumble, I wonder what gains, in terms of power, we would see if it were a EL header instead of UEL.

Either way, I'm always curious about the progress of your exhaust set-up.

Keep posting!
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