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Old 10-12-2018, 08:07 AM   #1
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Winter project: Exhaust!

So, itīs soon time to put the Box to itīs beauty sleep.. One of the planned winter updates is a new exhaust. Since I do not want to hijack someone elses thread I start a new one, I would love some input and support from the common wisdom..

The plan is to put parts together to achieve my goal, not buy a readily available system.

Criterias to meet:
1) Maximize whatever power can be gained from optimum exhaust
2) Reduce weight
3) Nice sound, without drone
4) No cel
5) Pass inspection & be somewhat environmentally friendly, so I will need a working cat.

Just reading my own criterias makes my head spin, so.. Yes, Iīll be needing some support.

The car is a 2003 S.
I now have the standard ROW-system with cast iron manifolds and only "secondary" cats, porsches oem rear exhaust with crios mod.

Letīs try to start with some reasoning.. My reasoning related to making power/torque is:

-Iīll need headers to achieve the scavenging effect, what we need here is not "back pressure" rather the proper gas-velocity. I want:
a) Egual length headers
b) Long tube headers (more power from mid to high rpm)

I find that most/some "ebay" headers are unequal length and/or short tube. So... I need to find a good Header-Candidate. Suggestions?

After the headers, I basically want to minimize back pressure. I look at this nice thread: Custom exhaust and wonder if I would get away with the following:

I put a 200cel cat just after the collector.
I put a resonator in the original place of the cat, and then another resonator at the end like in the link above. So the chain is: Header+cat+resonator+resonator.
I believe this will be a good flowing system and Iīll loose a lot of weight, but it might be far to loud.. or?



Any comments so far? Am I on the right track?
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Old 10-13-2018, 06:11 AM   #2
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In my humble opinion, I believe that you are over-thinking the headers.

Is this to be a no-compromise track-only car, where every last bit of power needs to be coaxed from the engine?

If not, I sincerely doubt that one header style vs. another will amount to any performance differences whatsoever, especially if your existing OEM exhaust manifolds are the Euro spec 3 tube into 1 style (as contrasted against those USA spec models which include the built-in cats).

But if you do have the USA spec built-in cat manifolds, then you may want to give this thread a read:

For Sale: Hollowed OEM Exhaust Manifolds, Complete with Mini-Cats
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Old 10-13-2018, 11:26 AM   #3
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Over-thinking? Me??

Hell yeah!!!!!

Actually, thats what makes it all fun to me, I mean the car runs great, I have got very nice sound and good power.. So, itīs obviously time to make things complicated. Itīs all a hobby and I love to go "all the way" in everything I do, so your observation is definitely correct!


About the headers not being equal length, I might be mistaken but from pictures of the "e-bay headers" I think it looks like un-equal length. But when I (over)think about it, that sounds strange, why produce headers with un-equal length?

I was out today on a great autumn-drive, thought about my exhaust plans and realise that if I go all in as intended it most certainly will be far too loud.. And droning, so. More over-thinking needed..

-To answer if this will be a no-compromise track car: No, the general idea is a "stealth track car", It must serve as a street car but be as capable as possible at the track. This means that I want to get rid of all the "low hanging" weight, so a lighter exhaust is one of many pieces in the puzzle.

Last edited by Robert986; 10-13-2018 at 11:34 AM.
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Old 10-13-2018, 06:05 PM   #4
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What I did:

OEM Euro 3 into 1 manifolds. I've wasted far too many hours of my life trying to make aftermarket headers fit properly in my various cars. With OEM manifolds, you know they will fit right the first time. They flow more than good enough for my needs, certainly as compared against the cat manifolds linked in my earlier thread.

Circuit Werks secondary "resonator" pipes. Note that all of the acoustical "stuffing" was quickly and amusingly blown out of them during their initial start up. If you wanted cats, then just select the C.W. cat convertor version instead.

Dansk "sausage" muffler. Very high quality, and a perfect fit. Bought used, scratches and dents as seen in the picture courtesy of the previous owner.

The combination of these 3 components sounds great, and I consider it to be my "perfect" system. Lots of that flat-6 character without any drone, and overall it saved me close to 50 pounds over stock.

DM









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Old 10-14-2018, 12:07 AM   #5
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Your installation looks really sweet Dave!

Would love that kind of weight saving, I will however go for aftermarket headers, at least in theory it should give some scavenging effect. Also, long term Iīll be addressing also the intake, and plan to do a re-map when the whole system is done.

So, no drone on that Dansk muffler? Thatīs great, found this video https://www.youtube.com/watch?v=imC4Jab7Zv4 but the sound on this video did not do it for me..

Sounds odd that the CW resonators didīt keep together, makes me wonder about their general quality. As you say I can order mid pipes complete with 200 cels cats, but if the quality is low on resonators, what gives that the cats would be ok? Anyone tried those?
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Old 10-14-2018, 07:38 AM   #6
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My setup, FWIW. Chinese headers, Fabspeed pipes with 100 cell cats welded in, Flowmaster single chamber mufflers. 2" tubing throughout.
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Old 10-14-2018, 09:35 AM   #7
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Quote:
Originally Posted by j.fro View Post
My setup, FWIW. Chinese headers, Fabspeed pipes with 100 cell cats welded in, Flowmaster single chamber mufflers. 2" tubing throughout.
Looks badass j.fro!!! Any drone? a bit on the loud side?
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Old 10-15-2018, 09:28 AM   #8
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By the look of it, those headers looks pretty nice https://www.ebay.com/itm/Porsche-Boxster-97-04-986-Exhaust-Headers-Manifolds-Stainless-Steel-w-Gaskets/263950658922?fits=Model%3ABoxster&hash=item3d74af6d6a:g:9EYAAOxy63FSsyqi

Any votes against?
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Old 10-15-2018, 09:52 AM   #9
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Those headers look like the same ones I installed on the beast , good price and good fit . Have been on the car over a year now no issues/cracks/leaks . She made 280 HP at the wheels so apparently they flow well also
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Old 10-15-2018, 10:09 AM   #10
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The sound is nice, and it's compliant with the SCCA noise regulations, which I believe is 96dB. There's a little drone, but it's not too bad. All in, the system was under $875.00
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Old 10-15-2018, 10:42 AM   #11
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Quote:
Originally Posted by rfuerst911sc View Post
Those headers look like the same ones I installed on the beast , good price and good fit . Have been on the car over a year now no issues/cracks/leaks . She made 280 HP at the wheels so apparently they flow well also
What brand name did you buy? It always good to get user feedback on Chinese headers. Is this for your 3.6? Did you dress/port the pirimary entries?

What muffler and pipes do have installed?
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Old 10-15-2018, 01:20 PM   #12
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Quote:
Originally Posted by jaykay View Post
What brand name did you buy? It always good to get user feedback on Chinese headers. Is this for your 3.6? Did you dress/port the pirimary entries?

What muffler and pipes do have installed?
I don't remember the brand sorry and yes on the 3.6 . The headers were installed " as is " with no port work or additional machining needed . From the headers I am running cat delete pipes then a GHL twin can muffler . The GHL muffler is a screamer with drone but I inserted Car Chemistry baffles into the tailpipe tips and that helped a lot . I may soon experiment with a Mille Miglia single can muffler that I can buy for cheap .
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