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Old 08-17-2014, 07:52 AM   #1
nvmylh
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Default Custom 4-1 headers -> terrible sound!

Hi all,
Writing from Melbourne, Australia, love the website!

So I built some equal length 4-1 headers, 1.625" (mild steel) pipes, 41.5" lengths, initially hoping to get some pressure waves arriving at the valves and valve-overlap period around 3000-3500RPM, but I think I mucked up a calculation and it should actually happen around 3750-4000rpm. No biggie.. The collector goes down to 2" then up to 2.25" pipe to the cat, then through a modified WRX STI (approx. 60mm OD) system from there on.

Anyway, it has definitely made my 2003 Outback go better! My LONG slightly steep test hill used to require going from 5th to 4th gear approx. half way up, now I can cruise straight up in 5th gear and it loves to rev without feeling like it is being choked above 3000rpm!

BUT, it sounds terrible... Quite a bit worse than I expected! I knew it would sound nothing like an unequal length system, but even still I think its pretty bad, even for an EL system. Any ideas?

In the video I only revved the engine to about 4500rpm as it has done 145,000 miles and i'm scared it'll blow a head gasket! (well at least until my spare motor is almost finished).

https://www.youtube.com/watch?v=7Cybpf1k1qA





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Old 08-17-2014, 10:36 AM   #2
vicious_fishes
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if the noise itself is irritating you (the volume etc) then wrap them in heat wrap.

but if you "just don't like" the sound of EL headers, then sell the car.
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Old 08-17-2014, 12:29 PM   #3
subi400
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What the OP needs is a much larger resonator in the midpipe.

Get a 24" resonator and then get a better muffler that has better internal packing and it should sound better.
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Old 08-17-2014, 01:47 PM   #4
dark hawk
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ya a larger resonator should help. Personally I think it's tolerable though.
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Old 08-17-2014, 03:26 PM   #5
EdHilario
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EL headers will make a Subaru sound more like a Honda
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Old 08-17-2014, 06:13 PM   #6
nvmylh
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Default

The volume is fine, its not that loud thanks to the big STI rear muffler and I don't mind the sound THAT much, its just so different to what I thought it might sound when building the system. I never expected there to be that strange vibration sound when changing gears too.

Does anyone think that the middle muffler/resonator in the STI system could do with being changed to a 24" hotdog or just add the hotdog?

I've tried to find as many ej25 N/A video clips with EL headers, the ones I did find sounded pretty good, almost and bit UEL style though.. I know my pipes will be well within 1/2" of equal lengths, I did the design on CAD and was able to measure the lengths as accurately as I wanted.

Heres some pic's of the rest of the system:


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Old 08-18-2014, 12:30 AM   #7
Zefy
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99 2.5TS (DEAD) / 87 GL

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Here is what mine sounded like.

TWE 4-1 EL headers with cobb catback. sti catbacks tend to be really raspy and tingy on an NA car from what i've found. The system i have still doesn't "sound like a subaru" but I don't care... more power! The old Cobb catback also has a fairly long (18-24" i'd guess) resonator which most aftermarket exhausts seem to skip.


And here is the same setup but with an AVO turbo kit. Basically just made it quieter and turbo sounds.

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Old 08-18-2014, 05:46 AM   #8
nvmylh
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Hey Zefy that top video sounds good! That's what I want mine to sound like but i'm not sure how to get the slightly deeper note (without going UEL). I'd rather power over sound too, like yours is the goal!
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Old 08-18-2014, 09:32 PM   #9
nvmylh
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After the few posts on here, i searched for 'raspy' subaru exhausts on google, found a heap of info with people having the same exhaust and sound as me. I'm now thinking of cutting out the sti resonator and putting in a 18" or longer resonator like the one below (measures 23.5" long). Its not exactly a brand name item, but its only going on an Outback, i'll see how it goes.

Lastly does anyone here think 23.5" is too long/big? There are 19.5" and 15.5" versions. Thanks again!
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Old 08-18-2014, 10:57 PM   #10
Back Road Runner
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Add in a resonator/glasspack and it'll cut out that rasp and quiet it down. NA engines are super noisy, so you can't really shy on muffling to get it down to a reasonable level. A good straight through muffler plus a large resonator/glasspack in the midpipe will get it down to a good level.
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Old 08-19-2014, 04:47 AM   #11
Zefy
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99 2.5TS (DEAD) / 87 GL

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ya for the resonator, get the longest you can fit. There are a bunch of videos on youtube of people putting sti catbacks on their n/a motors and they all have sound super raspy.

If you can fit the 24" one in there, do it.
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