Hello everyone and welcome to my first post on this board.

I will/should be picking up my new Z this week, and I've spent the weekend doing some research on alot of stuff.

I'm trying to understand the exhaust system on the Z. I see alot of headers and cat backs for sale but I don't see anything about cats. Are the cats before, after or part of the Y-pipe?

Some exhausts (the one's they claim to be "true dual") see to take over rigth after the headers finish. Am I right? Does that mean that the cats are included?

It just seem silly to change the header and the cat back if there's still a restrictive factory cat in the middle. On my current/previous car, I changed the cat back, then the headers but until I got a high flow cat, I hadn't unleashed it's true power.

Can anyone give me some insight? And does anyone have a good underbody picture that differentiates all of the exhaust sections?

Thanks,
Stef

 

cats are after the headers and before the y-pipe.

true dual exhausts still start after the cats. they are true dual because they dont converge into one pipe as the y-pipe systems do.

the cats are the most restrictive part of the exhaust and you wont get the full potential until you change out that part. people who just change out the cat back systems do it mostly for looks and sound... imho.

btw, welcome to the forum.

 

here is a pic of the underbody:

 

I love that pics...comes in handy

 

Awesome picture thanks.

Is there a company that makes a full system including headers, cats and cat-back. I saw that Borla makes a header and a cat back but what about the cats?

Also, with my previous car I had problem with a Check Engine Light because the o2 sensor threw a code for cat inneficiency. Does the Z have the same problem?

 

Well some get a check engine light and others dont. I got a Check engine light when i put my test pipes on. Reason being is that i have a turbo kit and the code was system running too rich. But skidazzle sells an o2 simulator that works great. No more Check engine light for me.

 

I have Helix test pipes which completely delete the cats. Where I live, there are no emissions testing. I also have the Injen dual exhaust which bolts up to the test pipes. I have a slight raspy sound due to the test pipes, but I can deal with it.

I dont have headers yet, but I have heard that the Borla headers do not make much power. A lot of guys are going with the DC Sports headers because they are cheap and are of high quality for the price. They are equal length, so they will bolt straight up to the cats or test pipes in my case. If I were to go with headers, I would go with a long tube setup like the Xerd or 350evo ones(when they come out). These completely delete the cats or test pipes and connect directly to your catback exhaust. They cost more, but when you figure in the price of high flow cats or test pipes and equal length headers, you are not really spending that much. I have heard that the install is where you spend your $$$.

Zach

 

Oh yeah, I have no CELs with my current list of mods.

 

I purchased the Crawford High Flow cats and the new Injen SES dual exhaust...I love the sound and performance (no dyno). I had them installed becuase I don't have access to a lift, it took them 1.75 hours...total install 135.00 and well worth it I'd say.

HF Cats 450.00
Injen 800.00

Aggressive sound under acceleration but barely noticably at cruising speed...I love it. Installer had put on 4 other systems on z's and said mine sounded the best by far...two were borlas and two stillens (one of the stillens was on a supercharged z and he said it sounded terrible)

Crawford V-5 plenum and front stabilizer bar this week then I'm done with mods for a while (per the wife).

Frit-z

 

cool thanks for the info guys.... keep it coming.

I'm getting really anxious to pick up the Z now

 

You'll find that the exact exhaust you select on this car makes little to no difference in the power gains.

The Dual Systems out there will bolt directly to the cats. The Non duals bolt to the Y pipe, and each branch of the Y pipe bolts to the cat. When you start comparing apples to apples (ie duals vs non duals with aftermarket Y pipes), you will see the power gains are extremely close to one another.

As mentioned, the cats are a very restrictive part of the exhaust, as is the factory Y pipe (it has a cat in it as well). These would be the two most important things to change...the rear most section would be to change the looks/sound moreso than an all out performance gain.

adam

 

The factory Y-pipe does not have a cat in it. Underneath all that heatsheilding is small, restrictive piping.
The car only has 2 cats. One on each side between the headers and Y-pipe.

 

so most of gains from cat and y pipe?
what kind of sounds does it put out if you just change cat and y pipe? deeper sound? is there sound clip available?
what would be the best combination of cat and y pipe?
thanks.

 

the most restrictive parts of the stock exhaust system are the 4 cats (2 in each pipe) and the Y-PIpe.

Replcing the Y-Pipe will give you almost as much gains as replacing the whole exhaust. Replacing the whole exhaust (depending on exhaust) will give you a large weight reduction...

when you change to high flow cats or test pipes it generally opens up the sound of the exhaust even more... it will be over all louder and more bottom end as well as more high end...

some exhausts stay quiet no matter what like the Fujitsubo...

 

thanks for info Jason.
is there anyone has just replace their cats and y pipes?
how is stock exhaust sound with that setup? deeper?
i want to get test pipe with y pipe but i don't want to end up bad exhaust sound.
thanks.

 

You mean that you didnt get a check engine light with the Nismo Oil Cap???