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Discussion Starter #1
Few enthusiasts coworked with exhaust tuner intensively here in
Taiwan.
they did a lot partition tests from headers to muffler

Here are some valuable findings to share
(1) Headers alone.............................. A TQ all the way
(2) Headers + mid pipe + muffler ........ A- not better than (1)
(3) mid pipe + muffler .......................... B++ less TQ in lower rpm
(4) Stock exhaust................................. B+
(5) racing cats + anything else .............B- much less TQ than (4)

Unlike Z, FXers need TQ very much
factory FX get an excellent exhaust, be calculated precisely to hold the TQ well in low to mid rpm zone.
 

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Interesting. The muffler is mainly for sound and has minimum impact on performance while on the other hand; I wonder why [email protected] insists that there is only ~50% gain utilized from their headers without changing the cats, which according to him are the most restrictive part of the exhaust.

From my experience with the RT and Crawford cats, they do provide a noticeable gain (at least past 4K rpm) and improved overall gas mileage. Was the ECU given amble time to adapt? Also, there are many manufacturers of different parts and they can't all easily clumped together to represent each category. Is an intake good or bad for the FX? It depends, right.

Good find but details would be more helpful.
 

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Discussion Starter #3
Indeed, had my headers bolt on this afternoon.
The lower band TQ keeps very well, it becomes even stronger
in over 3000 rpm.
I'm very happy with the headers.

In contrast, I'm also shocked to find another FXer with headers + nismo exhaust loss his TQ seriouly after test drove his car.

He once put metal cats to make it a complete free flow
then change them back a day after........ TQ is missing

Free flow do please Z & G35 guys everywhere......true !
but it works not that well in FX. :(
There's something different from FX to G/Z in exhaust design.
Not known yet. :oops:

My headers
 

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4400 pound SUV might be why. :? Needs Alot to get her Moving quicker/easier/faster, which is probably why the 4.5 is Better suited for the FX. (More Stock HP/Torque) Hindsight :oops:
 

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Discussion Starter #6
Stainless headers




Sincity said:
Benzo:
What kind of headers are those?
 

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Discussion Starter #7
Someone in Z forum post this "headers on" dyno chart


Regardless of the before/after hp number themselves.
In my butt dyno
I support the headers gain is very close to the above chart.

a different TQ curve sits right over the stock curve from the very low 2k rpm.
(1) Less effort to maintain 60~70 mph cruising.
(2) Faster accel. when doing 70~90 mph.
 

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Benzo

Where did you get your dyno done, I am thinking about getting it done too.

Jim
 

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Well I am running Stillen headers and cat back exhaust plus running kinetics cats, my exhuast has increased a few decibles since installing the cats.

Jim
 

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Discussion Starter #11
Mine is free, anytime .....butt dyno. :lol:
In Taipei, I'll recommend the HKS agent, they have a dynojet william had his ATI FX tuned there.


jimsbmw said:
Benzo
Where did you get your dyno done, I am thinking about getting it done too.

Jim
 

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Discussion Starter #12
many Fxers did exhaust mods more or less, the tone was changed
before headers......like jims

Find one headers only FXer, his tone is close to stock.
plus a little deeper , sounds good !

tazdevl said:
Any impact in terms of amount of noise and tone with the addition of the headers?
 

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Discussion Starter #14
One exhaust factory here, they made for orders coming from Japan mostly.
Few inventory left, I'm lucky to get one.
The others here GB Nismo headers, arrive soon.

Sincity said:
I meant who makes them?
 

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Benzo said:
He once put metal cats to make it a complete free flow
then change them back a day after........ TQ is missing
When I had the RT cats installed, there was a significant low and mid-range tq loss immediately afterwards. Two weeks later though and few more WOT's, most of the mid and bottom end came back but there was definitely more power at the top pass 4K rpm. When I switched to the C.Cats, it felt that I got slightly more low and mid range tq back but less top-end than with the RT's - aside of the quieter sound. Also, the new cats might produce strange chemicals that could throw off the ECU while they burn-in. Our ECU's adapt fairly well but they take some time with the new cats. Gotta leave the cats on more than one day to make a more accurate judgment.

Nice headers install.
 
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