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Discussion Starter · #1 ·
when i did my exaust I noticed either 2 cats in a row after each manifold or a cat and a resinator, which is it? I was told that some have it one way and some have it the other. how do I tell which one i have? my truck is a 4x4 w/offroad and the cats or what ever they are look like an egg shaped object with a pourus material inside(kinda looks like a cat.).
the other thing is, has anyone removed the resanators on there truck? did it make it sound good or bad? did you gain any performance from it?
 

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I do think the forward two are cats and the aft two are the resonators. Not certain though. JetTech, I believe, replaced his resonators on his last Titan with straight pipes. Maybe he can chime in here.
 

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Discussion Starter · #3 ·
the gibson exaust I got also adds another resonator. do I really need all 3 :?:
 

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I am guessing you have 4 cats. My Titan is also 4wd OR and it has 4 cats but my first titan was non 4wd and no off road and it had 2 cats and 2resonators. Both JT and myself replaced our resonators on original titans with straight pipes. According to JT's monitoring program he has we loss performance.

Easiest way to tell is the resonator looks nothing like the cat, if both of yours look similar you have 4 cats.
 

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I have since re-installed the straight pipes and have noticed an appreciable gain with them. When I first installed them my computer monitoring software was showing a higher percent load on the engine, but after having them on for about 6 weeks all has settled back to normal. My guess is the computer had not adjusted the fuel curve for the loss in back pressure in the beginning.

They make an aftermarket exhaust system bark nicely and give an all around gain in tq and hp.
 

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Oh sure JT, now you share that info!!!! :lol:
 

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Discussion Starter · #7 ·
thanks for info
 

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Getting back to the original question yes, some have 4 cats and some have 2. I can't for the life of me figure that one out. My LE 4x2 had 2 cats and 2 resonators, my SE 4x4 has 4 cats. Really weird....
 

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Discussion Starter · #9 ·
mabye offroad packages need 4 cats. to pass cleaner emisions, since they will be in "wilderness". sounds like a good guess to me
 

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Hey Smokedya, those def are cats. 4X4 have 4 cats, no reso's, 4X2 has 2 cats, 2 reso's. Some have mistakedly removed the rear cats thinking they were reso's. These rear cats don't look like a typ cat, in that they have no heat shields, but all the factory reso's basically look like a small muffler.

Possibly, the 4X4's don't have the reso's due to clearance issues?? There's no 0xy sensors after these, so don't no if it hurts or helps by removing them, but I left rear cats alone for warranty issues. There should be no warr hassles as long as you stay truly "cat-back". No clue as to why a 4X4 needs lower emissions than a 2WD, so don't know what the purpose of the rear cats would be.

Maybe someone with the factory service manual could look this up?!
 

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Discussion Starter · #11 ·
so I do know that my gibson exaust has a resonater right before the muffler, what will be the benifits of replacing that with a strait pipe? any draw backs to replacing it?
 

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SMOKEDYA2 said:
so I do know that my gibson exaust has a resonater right before the muffler, what will be the benifits of replacing that with a strait pipe? any draw backs to replacing it?
It will definately be noisier w/o the reso. I believe most aftermarket reso's on these catback systems claim that they flow very well, definately better than the oem ones, so if it were me, I'd install the reso. You could always replace it with a straight pipe later if you didn't like the sound/performanc. If I had the factory reso's, I would have definately removed them. I installed a reso with my AeroTurbine system because I knew for sure it would be way too loud w/o one. Hek, even with the reso it's plenty loud...lol!

I think Finnattic has some clips of his Gibson system with and w/o the reso's for comparison on this site and at TT.
 

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SMOKEDYA2 said:
so I do know that my gibson exaust has a resonater right before the muffler, what will be the benifits of replacing that with a strait pipe? any draw backs to replacing it?
I replaced the resonator on my Gibson system with a 3" straight pipe. It didn't make much, if any difference in sound. The real sound came from removing my aft cats and installing 2.5" straight pipes with the Gibson system. Now it sounds just right... :twisted:
 

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Discussion Starter · #14 ·
so you did remove your 2nd set of cats? are you worried about warrenty?
 

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SMOKEDYA2 said:
so you did remove your 2nd set of cats? are you worried about warrenty?
I'm not worried about warranty issues. I've monitored it with my laptop and OBDII cable to see how all the parameters are doing and everything is fine. Worse case scenario I would have to reinstall them for any warranty work and that only takes about 10 minutes. Actually the shop foreman at Nissan has already seen them and loves the way it makes it sound so I guess I'm not worried at all.
 

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Discussion Starter · #16 ·
thanks for info JT, we need that info on helper springs also, best mod you can posibly do to our trucks!!
 
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