Non Turbo Exhaust Guide

[Locke]

In all states in the USA, it is illegal to remove the catalytic converter on any vehicle that came equipped with one from the factory. Fortunately, some states have no emissions testing, and law enforcement doesn't check, or doesn't care.

 

[dr1665]

In all states in the USA, it is illegal to remove the catalytic converter on any vehicle that came equipped with one from the factory. Fortunately, some states have no emissions testing, and law enforcement doesn't check, or doesn't care.

Yup. It is Federally illegal to remove or tamper with any catalytic converter which is not malfunctioning. No legit muffler shop in the US will remove your cat unless they are replacing it with a new cat. (Some will even give you a hard time about replacing the old one if it's not actually bad because they can be fined for tampering.)

Decent write-up. Reminds me of this link for some reason. :shrug

 

[murray1]

Ok, I will try and word it a little better, it was late last night, I will also say that it is illegal to remove cat and add a little bit more.

Decent write-up. Reminds me of this link for some reason.

Similar but more in depth, will be even better when I get finished. It is also nice for people new to searching for stuff for their car because idk bout you but it took me a while to find out about 2gnt.com and I think this was the first site I came too, might have been dsmtalk though.

 

[murray1]

One question, I am searching some stuff up while I do this and I noticed a thread on ssautochrome header. Off their site it is 195 shipped to canada, thats about as good as it gets, from reading they sound good quality and everything too but those posts are 2004 just wanted to make sure, I am thinking about ordering these for myslef.

 

[murray1]

Ok, here is the revised edition, I added some more info and can't believe how bad my grammar/word choice was, I guess that is what happens when you type something at 2 am.

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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 accommodate your mods. In particular it is meant for a car that is following the Tech guides found on this site for either a 1g or 2g.

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 almost equivalent to 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 testpipe.

Catback

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. What is scavenging? It is the exhausts ability to flow freely and quickly. If you increase the size of the pipe too much then the exhaust pipe will not stay warm enough and the exhaust will creat turbulence both of which causes poor flow and in turn do not allow the engine to breathe properly. If you plan on going turbo though you may want to go 3" as 2.5" will be a little restrictive. There are many different brands of catbacks and choosing one will have a lot to do with your personal preferences. Although most of them will provide slight power gains the most important part is how it sounds. A couple common catbacks are Tsudo N1 and GReddy Evo 2. Tsudo's N1 catback off of ebay is a good exhaust that produces a nice sound for a good price, while GReddy's Evo 2 is known for great quality and nice deep quiet sound but comes at a price.

Header

A header is not going to make much of a difference in terms of peak power but they will shift your midrange powerband. In general a header will sacrifice a little low end torque but keep your power on hand longer once you get up in the revs. 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 torque compared to the 4-2-1 style and a 4-2-1 style will be more efficient at lower revs. 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 go turbo. There are a lot of different headers and you have to be careful with what you buy. The biggest thing is to do some research when you find one you think will be good. Many people that live in steady climates can get away with a cheap ebay exhaust but if your climate fluxuates stay away from them as they will most likely crack. Ebay headers are also known to say 4-2-1 design when they are actually 4-1 design so make sure you research the part number/model before buying so that you actually know what you are getting. One more thing about headers is that if you are not going for looks then a good idea is to buy header wrap to keep the heat out of the engine bay. Header wrap also slightly improves performance as it keeps the temperature up causing better flow.

Catalytic Converter/Testpipe

The most important thing you have to remember when deciding on what to do with your cat is that it is illegal to remove it and without it you will not pass emissions. That said depending on where you live you may not have emissions testing and it may not be strongly enforced. It is highly recommended that you check into how sticky your local emissions/police are on the subject.

Once you find out how your local emissions is enforced you have a few options. If they are really sticky ie. California your best bet is to stick with your stock cat, your only other choice is to go buy an expensive high quality high flow cat. If your emissions are not strongly enforced you can

A)Gut your cat which is not recommended for multiple reasons including noise, poor scanvanging etc.
B)Buy a quality high flow cat, keeps you legal and improves performance at a price.
C)Buy a cheap high flow cat or install a testpipe. Almost all cheap high flow cats are only resonators and do nothing in terms of emissions. A testpipe is just an extra piece of piping added instead of a cat.

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 if you choose choice C) is that you will encounter a CEL(check engine light) due to improper downstream oxygen 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 the raspiness and to decrease some sound level is to use a resonator instead of testpipe.

Hopefully this helps you understand the options available and decide on what you want to do with your cars exhaust. Doing these modifications will produce some power but more noticeable will be the change in exhaust note/sound level.

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Hopefully this is better. Again if you notice anything wrong/needing change just say so.

 

[murray1]

Hey, so was that post good enough to be made into a FAQ? Just wondering because no one replied.