Non Turbo Exhaust Guide

[murray1]

Ok, so I have been searching and searching and searching trying to figure out what is the best thing to do for exhaust on a 2g n/a dsm. For everything I have read there is an equal amount of posts saying that no it doesn't work or you shouldn't do that etc, way too many contradicting posts.

So I am starting this post to hopefully clear up a bunch of questions about n/a exhaust and create something like a guide. If you drive/own a turbo dsm please do not answer these questions unless you know for a fact that what you are saying applies to n/a cars and is correct. Hopefully with your help we can figure out what is actually best.

One more thing, this thread is meant to talk about the aspects of exhaust that pertain to performance and sound etc, not to talk about what brand of exhaust you have and if you like it or not.

Enough of the pleasantries lets get at it. Some of the topics that I feel should be addressed are

Headers

What can one expect in terms of HP and torque at different rpms?
How do they affect the sound of ones exhaust?
Is there any differences between a 4-2-1 and a 4-1 design other then the designs shape that one should be aware of (such as if they act differently in determining the power range etc)?


Catalytic Converters / Testpipes

How do stock cats, high flow cats and testpipes compare in terms of power?
Does gutting your stock cat provide an increase in power?
How bad do gutted cats/testpipes smell?
Will gutting your cat or installing a testpipe cause a either 1g or 2g dsms CEL to come on? If so is there anyway to fix this?

Catback Exhaust

What size tubing is best, stock 2 1/4 or 2 1/2 in terms of performance and sound?


If you have any other topics/questions please let them be known. These were the few things that I could think of at this time.

 

[Locke]

Have you looked or searched for any of this information yet?

You could try looking here and here.

 

[BigRand]

Header:
not so much a horsepower contributor as it shifts the power to become more useful, helps keep the power on hand.

4-2-1 header is obvouisly a 2 piece design, where a 4-1 header is a one piece. The one peice is a more durastic attempt at shifting the power band upwards and sacrafices more low end compared to the 4-2-1 design. (I'll leave the science behind that to someone else)

Your header will change the exhaust not a little bit, because its less restictive, however your cat and muffler determine the majority of what the car will sound like.

Highflow cat/Testpipe

Don't gut your cat...the cons out weigh the pros, and the cost of building a testpipe is realtively cheaper then all the platinum your discarding from the stock cat. (believe it or not but the cats are worth something)

If you do go with a test pipe, you will throw a CEL, there are a couple of different modifications (none that I have tried personally YET) but there is placing the spark plug spacer on the rear 02 so that the readings are less then if it was fully inserted.
And there is a resistor mod, to trick the ecu into thinking the rear 02 is getting the correct reading.

For those of you with emissions to pass, a highflow cat is always a good choice to be on the safe side. HOwever DO NOT purchase those "highflow cats" you see on ebay or the obx ones, as I have never heard of one containiing the materials nessesary to actually do the job of a highflow cat. Go purchase a magnaflow highflow cat, they start at about $100 and go up depending on size. 3" highflow cats are a littler harder to come by, but that would be for the turbo people.

Exhaust

I went with 2.5" piping as an NT because that was the size the product was sold in for the car.

If you a search on this forum regarding scavanging, you can dismiss any argument that backpressure is needed for NT cars. This is not true. Doing this research will also help you make a personal choice of weather you go with 2 1/4 or 2.5", one main thing to consider when upgrading exhaust if you do go to a exhaust shop, is to make sure they use mandrel bends.

Some decently priced exhaust systems for NT's are

Tsudo 2.5" N1 style exhaust on ebaymotors

P.I.T.'s 2.5" at www.horsepowerfreaks.com

both should be under $300

Greddy's Evo 2 is known for being a quality yet quiet exhuast, but its pricey

There is more, but as I just read you don't really care about which product types are better do you...oh well

 

[dr1665]

Ok, so I have been searching and searching and searching trying to figure out what is the best thing to do for exhaust on a 2g n/a dsm.

First of all, a 2nd Generation Non-Turbo DSM is a 2GNT. Now that we've got that out of the way, allow me to shed some light on the definition of "best," as it pertains to my exhaust recommendations below.

Dictionary.com defines best as an adjective meaning "most advantageous, suitable, or desirable: the best way. That being, what makes the best best choice of an exhaust system? In my opinion, and you can check my profile to see if it's of any value to you at all, the best exhaust system for a 2GNT is one which provides the greatest value. With that in mind, the following would be what I would consider the best VALUE exhaust for any 2GNT which is neither fully-built nor turbocharged.

• Pacesetter 4-2-1 Header (used)
• True High-Flow 2.5" ID catalytic convertor (NEW, from RRE)
• 2.5" ID catback - could be used, could be Ebay (GST system is fine)
• Dual tip muffler, painted flat black

The above system, including a brand new, $100 cat from RRE, should still be under $400. If it's more, you chose poorly. The system that follows is more along the lines of the best exhaust system I would consider doing more research, personally, upon for my own car which is A) fully-built and B) likely to make power beyond the factory redline.

• True long tube header (LTH), 4-1 design w/ merge collector
• True High-Flow catalytic convertor (NEW, from RRE)
• 2.5" (maybe 3", I don't know yet) straight-route piping
• Dual tip muffler, painted flat black

This system would likely run more than $800 due to the custom fabrication required. You could run such a system on your own car, but custom fabrication requires not just some buddy with access to a welder. You have to do your homework into exhaust theory (parallels fluid dynamics if that helps) so that you at least have a general understanding of not only what changes to a design have what affects, but proper fabrication techniques.

Despite there appearing to be a lot of dissension among owners when it comes to exhaust system selection, in the end, your best bet is going to be to pick the system which you think looks the best. Whether the car is on or off, you can always see it. The next factor is sound. When you're in the car, you'll hear it. You don't want your car to sound like ass when you get on it, so sound is important. Finally, you want to consider the price. Don't spend more than $500 on your exhaust system (or more than $300 on a catback) unless your engine is done and you're going to broke. You'll just be pissing the money away. On a BPU'd 2GNT, the power gains associated with an exhaust are hardly worth talking about, imo. A nice exhaust does more to make the drive more pleasant than fast.

Now get back to your research.

 

[bullettdsm]

Um, too hard of a question. Too general and too subjective (at the same time).

Sound = subjective

Size = goals

Full exhausts should match the set-ups they are on. It depends on your set-up.

And Driggs, so far my emperical research is leaning toward 2.5" (maybe EVEN less depending on wall thickness). But I haven't tested out the Crower 3 engine yet

MB

 

[murray1]

Um, too hard of a question. Too general and too subjective (at the same time).

Sound = subjective

Size = goals

Full exhausts should match the set-ups they are on. It depends on your set-up.

To try and clear this up I meant this to be for a 2g, i think 1g would be similar but have not researched them very much as I do not own one. I am meanging this to be an article for people to use for cars with little to no mods other then lets say free mods, air intake and possible other little things. No major performance mods, turbo etc. From dsmtuners tech guide for 2gnt

1. Air Intake
Replace your stock air box with a solid pipe and high-flow cone filter.

2. Cat-back Exhaust
Replace your stock cat-back exhaust with a higher flowing model.

3. High Flow Cat
Replace your stock catalytic converter with a higher flowing model.

4. Exhaust Header
Replace your factory exhaust manifold with a tubular steel header.

People that modify there cars further will most likely know what there mods are going to do to there car and whether they are going to need something different in terms of exhaust.

Also when it came to me asking about the sound changes of each product I meant does it make the exhaust note higher or lower. In case of testpipe and gutted cat does it greatly affect the loudness of exhaust? If you do install one of these, is it a good idea to add another resonator or something to bring down volume? I do realize what sounds good depends on the person but I meant the actual measurable differences such as pitch and noise loudness.

Have you looked or searched for any of this information yet?

You could try looking here and here.

Not sure what these are supposed to be, nothing helpful comes up . I have searched and I do realize that this kind of sounds like a simple question but it really is hard to find the information and believe what you are reading is right.

Header:
not so much a horsepower contributor as it shifts the power to become more useful, helps keep the power on hand.

4-2-1 header is obvouisly a 2 piece design, where a 4-1 header is a one piece. The one peice is a more durastic attempt at shifting the power band upwards and sacrafices more low end compared to the 4-2-1 design. (I'll leave the science behind that to someone else)

Thanks, this helps out and conforms to some of what I have read. Am I right in saying that with headers you lose a little low end power and gain some at higher rpms? Approximately how many rpms would you expect this to shift? Do headers also increase the size of power band? So 4-1 sacrifice a little more low end compared to 4-2-1, do they gain a little more at top end in comparison or are they just less efficient overall? I am guessing that it depends on quality and design but just an overall for comparing something like Pacesetters cheaper 4-2-1 header to Meghan's 4-1 header.

As for what you stated that is what I had thought after researching them but had seen people saying that it was opposite for them and that they thought they gained low end and and their power band was nice until higher rpm where the power dropped. In most of those posts it kind of sounded like they needed to port exhaust and such because of using cheap headers but just wanted to clear this up.

Highflow cat/Testpipe

Don't gut your cat...the cons out weigh the pros, and the cost of building a testpipe is realtively cheaper then all the platinum your discarding from the stock cat. (believe it or not but the cats are worth something)

If you do go with a test pipe, you will throw a CEL, there are a couple of different modifications (none that I have tried personally YET) but there is placing the spark plug spacer on the rear 02 so that the readings are less then if it was fully inserted.
And there is a resistor mod, to trick the ecu into thinking the rear 02 is getting the correct reading.

Exhaust

I went with 2.5" piping as an NT because that was the size the product was sold in for the car.

If you a search on this forum regarding scavanging, you can dismiss any argument that backpressure is needed for NT cars. This is not true. Doing this research will also help you make a personal choice of weather you go with 2 1/4 or 2.5", one main thing to consider when upgrading exhaust if you do go to a exhaust shop, is to make sure they use mandrel bends.

I wasn't really thinking about gutting my cat until I read up that with testpipes the lack of backpressure actually will hurt your power. Again I always thought, and what you say confirms that this isn't true and that the loss of backpressure will not hurt us. If someone has hard evidence/proof that it does hurt your performance I would gladly hear it.

BigRand do you remember any places that explain either of the two "fixes" for getting rid of CEL?

Some decently priced exhaust systems for NT's are

Tsudo 2.5" N1 style exhaust on ebaymotors

P.I.T.'s 2.5" at www.horsepowerfreaks.com

both should be under $300

Greddy's Evo 2 is known for being a quality yet quiet exhuast, but its pricey

There is more, but as I just read you don't really care about which product types are better do you...oh well

Thanks again. I personally am planning on the Tsudo exhaust for my car. I do care about which products are good, just didn't want this thread turning into I have a pacesetter cat back and love it thread. Which would eventually lead to an is Ebay exhaust really that good argument See what I mean

With that in mind, the following would be what I would consider the best VALUE exhaust for any 2GNT which is neither fully-built nor turbocharged.

* Pacesetter 4-2-1 Header (used)
* True High-Flow 2.5" ID catalytic convertor (NEW, from RRE)
* 2.5" ID catback - could be used, could be Ebay (GST system is fine)
* Dual tip muffler, painted flat black

What does a dual tip muffler painted black do to be considered the best value? This is pretty close to what I was personally going to do except I had been going towards a testpipe.

This has got to be one of the longest replies ever , sry about that hopefully cleared some of this up.

 

[SurrealDSM]

my car ran strong up until i blew my highflow cat so now my power is down the drain till i replace it so i must say a high flow cat is the way to go rather they gutting the cat your just sacrificing hp IMO

 

[Locke]

This link concerns exhaust backpressure. This same information has been gone over many times around here, including by myself. Here is another link if you are not so convinced about our FAQ article on the subject.

p.s. I fixed my links from my earlier post. They point to searches of countless other threads about the same stuff.

 

[murray1]

Locke thank you very much for providing the FAQ on backpressure. I read it and it makes a lot of sense and cleared up some questions. I probably didn't find it earlier because when I search I usually search just the 420a forum so don't have to spend 4 days to find something.

Really though Locke, do you think that I didn't search up the words exhaust or cat? That is why I said that I was seeing too many contradicting posts and wanted to clear this up, just like what that backpressure FAQ did. I am hoping after this thread is finished that either myself or another member can write up a FAQ or something on non turbo exhaust.

 

[Locke]

I suppose I ought to be more productive with my posts.

Loudness and raspiness will increase when pipe size in increased, or when using a test pipe, as the exhaust gas cannot smooth itself out.

A 4-1 header will become efficient at higher revs, while a 4-2-1 will be efficient at lower revs. The amount they effect power is dependent on collector style, whether or not it is stepped, diameter, radii of bends, and length of straight sections. (if any) With peoples varying levels of NA build, the volume of gas leaving the engine at given points may be different, thus changing where the header will become efficient. That is not mentioning the goals of the user.

In short, if everybody could fab their own exhaust system, from header to muffler, and have it "perfect" or "optimum" for their setup and goals, nearly everybody's exhaust system would be different. The improvements one may have over the other would be minor.

Buy what you think sounds and looks good.

 

[murray1]

Loudness and raspiness will increase when pipe size in increased, or when using a test pipe, as the exhaust gas cannot smooth itself out.

Are there any good simple ways to resolve the raspiness of using a testpipe?

 

[VelocitàPaola]

Try replacing the test pipe with a resonator. That or use slightly smaller exhaust piping, or get a muffler that actually muffles an appreciable amount (i.e. not a straight through design).

 

[murray1]

My oxygen sensor is going right now and I was searching up information on them when I came upon this thread.
http://www.dsmtuners.com/forums/showthread.php?t=242461&highlight=oxygen+sensor

Inside of it there is a link to this page.
http://www.dsmtuners.com/forums/showthread.php?t=221951

They both talk a little bit of how to trick ecu so that you don't have to worry about CEL after removal of cat or something else like this.

 

[Locke]

My oxygen sensor is going right now

If your front o2 sensor is going bad, replace it. You need it. If your rear is going out, or you plan on removing your catalytic converter, you can build a simulator to prevent that CEL.

 

[BigRand]

Just wanted to ask 2 questions.

#1 Are you making any money off this information?

#2 I thought I read that it was for a tech guide....is that for this website or 2gnt.com?

Okay and last but not least when you are righting this article if your going to be gramatically correct (something which I'm not sometimes myself)

Make sure you start refering to headers as a header....our Inline 4cylinder motors only have one header not 2 like v8 or v6's, or boxer style motors

 

[murray1]

Just wanted to ask 2 questions.

#1 Are you making any money off this information?

#2 I thought I read that it was for a tech guide....is that for this website or 2gnt.com?

Okay and last but not least when you are righting this article if your going to be gramatically correct (something which I'm not sometimes myself)

Make sure you start refering to headers as a header....our Inline 4cylinder motors only have one header not 2 like v8 or v6's, or boxer style motors

1) Nope, I wanted this information for myself and thought hey why not take 10 minutes when I am done and try and make this a lot easier for others.

2) Here, was at first going to put it on dsmtalk but they don't deserve one now. Just check this out to see what I mean.
http://www.dsmtalk.com/forums/showthread.php?t=181435

As far as the headers thing goes if I am referring to changing the header on the car I will use header and if I am saying something like headers will decrease low end power and increase upper end power I will use headers, because I am not referring to having two headers on the car but headers in general.

 

[murray1]

If your front o2 sensor is going bad, replace it. You need it. If your rear is going out, or you plan on removing your catalytic converter, you can build a simulator to prevent that CEL.

Yeah I am just looking around for a o2 sensor now. I checked local stores and they want $130 canadian. Online I have found 2 different stores that I am thinking about purchasing from.

One of them is a bosch from autopartsgiant
http://catalog.autopartsgiant.com/i...ID=24M1DHTKW24N0YZ5BG&clientid=autopartsgiant

Automedicsupply.com has two, one is a denso, one is a walker.
http://www.automedicsupply.com/catalog.php?&pkey=1103241#Location0

I have noticed on a couple threads that some of the sensors come with wrong plug, I believe it to be bosch but cant remember. If so is 13399 the correct part #? Could someone tell me which of these is the best bet? Also can driving with a bad oxygen sensor do any "damage"? It idles like crap and hesitates but I would like to save half the price unless it could mean engine damage.

 

[dr1665]

2) Here, was at first going to put it on dsmtalk but they don't deserve one now. Just check this out to see what I mean.
http://www.dsmtalk.com/forums/showthread.php?t=181435

If you got bent over that single comment linking you to 2GNT, which is the singular source of all technical information pertaining to the 2GNT DSM platform, then you must not be too familiar with that site, as they have been known to really turn up the heat. Even so, it's a shell of it's former self. The original Talkers reformed as DSMsource.

Appreciate the link, though. Nice to meet an Evo owner in my hometown who refers to 2GNT owners to 2GNT and is looking to pick up a GVR4. Haha. Ironic as hell.

The simple answer to your exhaust question is that there is no simple answer. As no two cars are modded exactly the same, there is no way to come up with a set list of components which make up the ideal exhaust system for a 2GNT. All the important information has been posted time and again on numerous boards. It's up to you to determine what you need right now an whether or not it's worth investing in something for you to grow into with more modification.

You can't just say "higher flowing," as that's still too vague if you don't know what you're talking about. A 3" exhaust will outflow a 2.5" exhaust, but only in the top end. A 2.5" system will flow better when the engine flows a lesser volume of air overall. If you want a rule of thumb, here, this is really all you need to know about exhaust system shopping:

1. Unless you're making more than 300hp, 2.5" is all you need.
2. If you live somewhere it snows or rains a lot, then you want stainless piping.
3. Mandrel bends are better than crushed bends.
4. Invest in a TRUE high flow catalytic converter. $50 Ebay units are NOT cats.
5. Unless you have a fully built engine running on the ragged edge, you're not making more than 15whp with any off-the-shelf exhaust system.

 

[murray1]

No that is not my only problem that I have/had with dsmtalk but I don't get why everyone thinks 2gnt.com is so good. It doesn't have that much information and the forums suck to use unless I am missing something.

 

[Locke]

No that is not my only problem that I have/had with dsmtalk but I don't get why everyone thinks 2gnt.com is so good. It doesn't have that much information and the forums suck to use unless I am missing something.

While I do agree that the board software used by 2gnt.com is less than intuitive, (at least for the likes of me) I disagree with the statement "It doesn't have that much information". 2gnt.com stores a wealth of information about 2gnt's. Much of the information found here on tuners likely originated from 2gnt.com. You have to search, search, search, and read, read, read, just as you would to find information on any board.

 

[dr1665]

EDIT:
I was just asking for a "TLDR."

When viewing the main index on the 2GNT forums, you need to be sure to select:
-Expand conferences
-Choose dcf view

Then you click on a sub-forum and select:
-Collapse topics
-View in threaded mode

Finally, select:
-Topics sorted by: Last updated date.

It can be confusing at first, but once you set those options, they stay that way and it works just like any other board you've been to. The most recent threads are at the tops of their respective sub-forums, and everything is quite intuitive.

Here's some food for thought...

If I didn't have a great deal of respect for the people who keep Tuners alive and kicking, and for the NT guys who work hard over here to ensure that other NT owners not on 2GNT still get quality technical information and guidance, I wouldn't even be here. I've worked hard over the years, learning all that I could about both platforms - 420A and 4G63 - so that I can help as many DSM brothers and sisters as I can, but as administrator of 2GNT.com, I can't just sit back and let some comment like "I don't get why everyone thinks 2gnt.com is so good. It doesn't have that much information and the forums suck to use unless I am missing something" slide.

You are missing something. You're missing a lot. Your car has more in common with a Dodge Neon than anything else on this board, Talk, or Source. I'd venture to say that 90% of the volume of technical information on this site doesn't even pertain to the cars in this section. On 2GNT, 90% of the information does. Don't try to start up the debate of the century around exhaust system theory for a 2GNT like it's never been discussed before and then brush off my site as being sub-standard when it's the source of 90% of the technical information you'll find about a 2GNT anywhere else on the web.

Sorry if I sound a bit steamed, but you just said my home, my family, sucks.

 

[murray1]

Whoa, I never meant it that way. I have looked at 2gnt and have found some pretty fair stuff but not in the forums part. If you don't look in the forums then there isn't that much information on the site. The reason I didn't look through the forums is because I didn't know you could make the changes you have below and without them the site is hell on earth to try and navigate/search/read. With your help it should be a lot better to get information off of. Thanks a lot for a helping post when you could have just flamed me.

Could anyone provide me with any of the information on the oxygen sensor questions, it is becoming really annoying and worse fast. My CEL came on twice now and both times was front oxygen sensor and now I am just leaving it on.

 

[dr1665]

I have looked at 2gnt and have found some pretty fair stuff but not in the forums part.

So you found stuff in the wiki, then? Excellent. So you know, the reason there isn't a whole lot there right now is because the wiki is only about six months old. It used to look like this.

No harm. No foul. 2GNT is just important to me.

As for the O2 sensor...

• When it's out, the ECU runs in a sort of "safe mode," wherein in reverts to some pretty ugly fuel maps to prevent lean conditions and detonation. This allows you to drive the car, but you're going to experience driveability issues as a result. I wouldn't worry about it too much, but I'd replace that FO2S ASAP.
• I think I've heard some stories about the Bosch too, so I'd probably pick up the Denso, myself. Although it doesn't really matter, when you consider that you will have the right plug - even if you have to cut it off the old sensor, right? I don't even know what kind of connector I have on my Galant. We cut the old one off (melted a bit on the manifold) and used some kind of screw together aircraft connector. If you have to change plugs, just be sure to connect the wires correctly.

Hope the settings info for 2GNT helped some of you guys out. It's not the prettiest forum out there, but I'll be damned if you don't get used to it really quick.

Latz

 

[murray1]

OK, sorry it took me so long to do this, I have been busy the last while. Here is what I hope is good to add to the new 420a FAQ

--------------------------------------------------------------------------------------------------------

420a NT Exhaust Guide

This is meant for a NT Talon/Eclipse with few mods, depending on what mods you have/have planned you may have to make changes to accomodate your mods. In particular it is meant for a car that is following the Tech guide for 1g and 2gs. There are a few different things that one can do to your exhaust to add a little bit more power and change the sound. One common thing to do is to swap out your catback exhaust with a used GST's catback, I haven't done it but I hear that it sounds good and increases power close to the same as an aftermarket mandrel bent catback. Another choice is to buy an aftermarket catback. With either of these choices you can also add a header, high flow cat or just install a testpipe.

When it comes to choosing a catback or creating your own you will probably want either 2 1/4" or 2 1/2" piping any bigger and you run into scavenging issues. You may want to go 3" if you plan on going turbo soon though.

When it comes to a header you are not going to notice much in terms of peak power change but you will notice a shift in your midrange powerband. In general a header will sacrifice a little bit of low end torque but keep your power on hand longer. There are two main types of headers for our cars, 4-2-1 and 4-1 style. A 4-2-1 style are usually a two piece style, where as a 4-1 style header is a one piece. For a daily driver a 4-2-1 style header is recommended as the 4-1 style loses more low end tourque compared to the 4-2-1 style. If you are making a race car and plan on running at higher revs then a 4-1 style header is good as they are slightly more efficient at higher revs. Installing a header decreases backpressure, increases noise level and can produce a raspy tone. Another thing to remember when thinking about installing a header is that it will be of no use if you plan on going turbo.

When it comes to your catalytic converter you have a few choices again. You can gut your cat which is not recommended for multiple reasons including noise, poor scanvangeing etc. The recommendd choices you have are to buy a high flow cat or install a testpipe. The biggest thing you have to remember when deciding on what to do is that in many areas it is illegal to remove your cat and in many states you have emissions testing. The best thing to do is to check into your local requirements to see if you can get away without a cat otherwise you will need to keep your stock cat or buy a real high flow cat. If you are going to buy a high flow cat make sure that you are actually buying a cat and not just a tespipe/resonator as most cheap high flow cats are not really cats.

Installing a testpipe/cheap high flow cat will decrease backpressure dramatically, a common misunderstanding about backpressure is that a lack of it will cause a loss of power, this is not true and a good article to read about this subject can be found here. One issue you will encounter if you install a testpipe will be a CEL due to improper downstream o2 sensor operation. A way to get around this can be found here. Testpipes will increase the sound level of your exhaust and often cause raspiness, one way to help eliminate this is to use a resonator instead of testpipe.

Hopefully this helps you understand the options and decide on what you want to do with your cars exhaust. Doing these modifications will produce some power but more importantly is to try and get a setup that sounds good too.

--------------------------------------------------------------------------------------------------------

Any changes/grammar corrections are gladly accepted and I hope this is good enough to be a FAQ article.

 

[BigRand]

Its a little wordy, in stead of "when it comes' six or seven times, just label each section with the subject of that paragraph. Also You might want to use bullet points with the explaination of why someone should use this method and if applicable why not underneath.
Different pronouns might be a good idea too.