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Discussion Starter · #1 ·
I recently installed OBX 4-2-1 race headers and it sounds like a fart can now. i believe this is happening because the new header has a bigger end diameter than the stock cat and now the air going into the main pipe is being restricted. I cant afford an exhaust system right now so is there anything i can do to make that horrible sound go away?
 

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Are you still running the stock exhaust system?
Can you take video of this so we can hear what your dealing with?
 

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FF's Night Security
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Eeww I bet it does sound bad lol. It'd probably sound better with the lunch box back on there lol. To sound good or decent you should get a exhaust like the FSwerks stealth exhaust. It will quiet it down alot and sound better. The OBX collector is 2.5" the stock exhaust is 1.78" or that's the flex that's that big? I think it's the flex, and the stock exhuast is 2". I have a full 2.25" exhaust including the flex, but with out the first resonator like in the stealth. Let me tell ya, it's loud and in your face lol.
 

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I recently installed OBX 4-2-1 race headers and it sounds like a fart can now. i believe this is happening because the new header has a bigger end diameter than the stock cat and now the air going into the main pipe is being restricted. I cant afford an exhaust system right now so is there anything i can do to make that horrible sound go away?
I just did the exact same thing you did.I couldnt afford both all at once so i decided to just get the header first and drive on it a while get it tuned a little bit with the wideband because thats the whole reason i got the header so i could get the best datalogs with the wideband.

Next ill get the catback or what ever they call it. Im deciding on what i want to put on it. I dont want to go with what everyone else is running.

I like how it sounds at low RPM and at an idle. Once i step into it i agree is sounds like crap. I kinda expected it though. Im just glad its not any louder then it is. I can live with this for a few weeks.

Do you notice more ratteling in your car? Now with the header i hear ratteling noises in my dash and some of the panels in the back hatch. My car sounds like its falling apart now! [:(] It seems to run a little better though. Cant wait till i get the rest of the exhaust and see how it really wakes up.

Im still burning all the paint off the heat wrap, i wrapped mine with that titanium, DEI heat wrap then i used almost a whole can of wrap sealer on the wrap. When i run it really hard i still smell just a tad bit of paint still burning off.

So whats your plan now? Do you have a wideband and a tune?

The fswerks catback looks ok but i want a longer center muffler, and i want an oval or rectangle type flat muffler in the back. I want everything tucked up under the car tight.

i believe this is happening because the new header has a bigger end diameter than the stock cat and now the air going into the main pipe is being restricted.
I think it sounds like a fart cannon because its smaller after the header your right, but its louder because you got rid of the front cat. (its so restrictive) I also think the header is made of different metal that makes the sound louder. The stock setup is cast iron and i dont think it rings or resonates the same as the stainless steel. Might be a reason the use cast iron?

This is another reason i wrapped mine, i had hoped the cloth wrap would help dampen that tinny ring sound. We should compare the sounds. I wrapped mine with about 40' of 2" titanium wrap. Not alot of overlapping but i think enough to help with the sound.
 

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FF's Night Security
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Header wrap does not effect sound, once again trust me on this one. I've had my header wrapped and unwrapped. What effected the sounds was the removal of the cat and on top of that the lunch box is gone. Also the diameter of the pipe effect it also. I added the flex later on, and I even had a crappy magnaflow custom exhaust with crush bends on it before. Sounds better with the "real" magnaflow exhaust but it's still loud and in your face. I want to add a resonator one day.
 

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Well it probobly isnt enough to notice but before i wrapped it i hung it up and i hit it with a wrench and it rang like a bell. After the wrap and paint it didnt have near the same sound. You could hear the metal but not a long ringing sound like it did without the wrap. It deadened it quite a bit.

Not sure what it does after its been heated and it burns and molds to the header?

Im sure the heat isnt a huge gain either but every little bit helps and eventually it all adds up.
 

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FF's Night Security
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Oh I don't doubt it made it sound different when hitting it. Maybe I didn't notice much of a difference on mine cause I didn't use any spray? Lasted for a long while too, about 4-5 yrs. After that it was rotted and would just turn to dust when touched. Now I don't know if there is much if any difference in sound coming out the tail pipe between a bare header, wrapped but not sprayed, and a wrapped and sprayed one like yours. I will tell you that putting the bigger flex on changed tone/pitch or what ever you want to call it, but was still loud and raspy that only a cat or a resonator could get rid of. Do you know what I am saying?
 

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Discussion Starter · #11 ·
i hear a bit of rattling not much though. but can you suggest me a decent priced system that will not be too loud? and if i get a cat back will i still pass inspectio. even though the old cat attached to the manifold is gone?
 

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i hear a bit of rattling not much though. but can you suggest me a decent priced system that will not be too loud? and if i get a cat back will i still pass inspectio. even though the old cat attached to the manifold is gone?
Nope.
The removal of the Cat is a big,fat illegal no no.
Seriously,try a custom exhaust shop to make You up a good sounding exhaust.
 

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so even if i get an exhaust with a catalytic converter it wont pass?
My brother has a toyota scion and it only has 1 little cat after the header.

Mine had on IN the manifold and one after, so ide think mine is still "legal" it might not be legal sound wise but ill tell ya. Its kinda loud but no where near as loud as some of those harley motorcycles i hear go screamin by when i have my windows down and they go flyin by. Some of those motorcycles are rediculously loud IMO.
 

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so even if i get an exhaust with a catalytic converter it wont pass?
I think installing a high flow Cat wont work on the zetec for emissions,as its too far removed from the original position to be heated properly to keep the o2 sensors readings correct.
I am unsure of NJ's current inspection laws but in Pa,if your under 5000 driven miles in a year,You are emissions exempt.
Anybody know the laws in You location?
 

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Discussion Starter · #17 ·
im not sure what the laws are here, but if were to buy just a magnaflow muffler and keep my piping would that stop the fart cannon sound? im guessing not but im not totally sure so let me know if i can cause buy just the muffler will be alot better than a whole system for me financial wise at this time.
 

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Hatch Nation #136
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Removing the cat, which is part of the exhaust manifold on a non-SVT Zetec and remving the resonator are what is making that noise.

You are basically running a race exhaust through a muffler build to quiet down a stock system. You can do a couple of cheap things to tone it down, like adding a high flow cat or SVT cat, and then tacking in a glass pack before the muffler to tone things down, but you don't want to waste the money on all that if you have long term goals to do a full exhaust.

Check out the systems that Trubendz.com has. There are some decent low cost options that might be the right route for you.
 

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Discussion Starter · #19 ·
thanks, i checked out trubendz and i was looking at just a tubing kit, if i bought this tubing kit and then a magnaflow muffler and put it all together, would it get rid of that sound? and if so what size piping should i get it in? im guessing 2.5 because the collector of the obx header is 2.5
 

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Hatch Nation #136
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Running 2.5 all the way back should be plenty, since you aren't running a turbo.

Make sure and get a kit that uses a resonator, so that you can deepen the tone and not sound like a Honda.

Are you just driving it around with the check engine light, since your EGR system, cat and O2 sensors aren't doing what they should or did you get a tune?
 
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