Titan Exhaust System Question

[SoCalBluetooth]

I've started a new thread because the discussion got off topic and I am looking to increase my knowledge of the system. The following are some pages from the factory service manual. I was told the bulged part of the exhaust pipe is the CAT however the manual does not agree with this.

My question is, what the heck is it? I am going to install a dual exhaust and would like to better understand the stock system before I go hacking it up.


The above pic shows the bulged pipe. Note that it is located after the oxygen sensor.



The above pic shows the exhaust manifold with the 3 way catalyst.



The above pic shows the catalyst located between the A/F sensor and the Oxygen sensor. The bulged part of the exhaust pipe is located after the oxygen sensor. See the next pic.



The above pic shows the bulged part of the exhaust pipe. Note it is called exhaust tube.


So come on, there has to be opinions. I for one think the bulged pipe is designed to insure proper operation of the oxygen sensor.

[Slurppie]

First off, the manual does not reflect the currect exhaust system being installed on the Titans. Starting at the exhaust manifiold you have the first buldge which is the pre-cat then from there it goes into either the resonator or the main cat depending on which version of the exhaust system you have. After the resonator or CAT it goes into the Y pipe then on to the muffler. If that's a pic of your setup then you my friend have CAT's instead of resonators. When installing an exhaust system it's against the law to remove the main CATS but since there are no O2 sensors post main CAT, the ECU will never know.

[greasy]

Those "bulges" are the resonators.

[juma]

Originally Posted by greasy

Those "bulges" are the resonators.

yeah, ditto. to confirm take your exhaust pipe loose on both sides and push out of the way and look up in there with a flashlight. you should see it go straight through. if you see it is blocked with a honeycomb looking obstruction, then its a cat. I've never seen report from someone who looked. usually though, if it is another cat, the oxy sensor would be behind it.

I have looked in mine that has different "little muffler" look and it goes straight through meaning it is a resonator.

juma

[SoCalBluetooth]

First off, thanks guys for your thoughts. I took Juma's advice and dropped the exhaust. Slurpmeister, you were right, the bulged pipes are CAT's. I've attached a pic. Now comes the hard part. Do I remove the CAT's or leave them on when I go to the dual exhaust. I'm inclined to leave them on to avoid possible dealer hassles and smog inspection problems down the road. But, would I see a performance gain by removing them. I could always have them taken out and add a flange so that they could be put back in if needed. What do you guys think?

[MikeZ]

From someone who has modded my exhaust system, you definetly have the secondary cats, NOT resonators. I would be more then happy to show a pic of the resonators that I removed if you need.

[SoCalBluetooth]

Do I remove the CAT's or leave them on when I go to the dual exhaust. I'm inclined to leave them on to avoid possible dealer hassles and smog inspection problems down the road.

But, would I see a performance gain by removing them. I could always have them taken out and add a flange so that they could be put back in if needed. What do you guys think?

[MikeZ]

just my opinion but I doubt nissan has any idea whether your vehicle was originally equipped with the secondary cats or resonators. I am starting to doubt whether they know why some has cats and some have resonators . I removed my resonators and have been told by service manager as long as I dont fool with cats, I am okay. I was very pleased with performance gain by opening everything up after cats.

Here is a thread on my exhaust:

A new exhaust configuration!!

[SoCalBluetooth]

Mike,
You got one nice exhaust system there. One question. Why do you opt to do without a Y or X pipe? Did you feel it would hurt you on the low end or what?

[MikeZ]

socal,
The magnaflow has an internal crossover which eliminates need for x or h pipe. If you went flowmaster dual in/dual out then yes, you would more then likely need a x pipe. I am very pleased with the performance AND sound. At highway cruising speed with stereo off, you can barely make out a slight rumble. But at all speeds, get on the gas and she talks!! I have not encountered any ear ringing/ head vibrating drone and its been on there about 3 weeks or so now so I think it would have surfaced by now.

Let me know if you need anyting else, more then happy to help.