Header/exhaust setup question

[NMTerras]

For the group:

My Thorley headers are here, waiting for some hardware to begin install. I have a choice to make, and would like some input. Right now, I have a Gibson catback installed, with 2.25" pipe. I can leave it in, and bolt the Thorleys up to them. Alternatively, I can run some new 2.5" pipe, and install a magnaflow super 44 I have sitting in the garage (my original plan). But...am I better off with the 2.25" diameter pipe? more appropriate backpressure? This is a little above my paygrade, so input appreciated...I have about a week to make this decision...

 

[granitex]

I would just run what you already have in there. Did you pick up a pair of CEL eliminators already? If not, you will want to before you get started on this project.

Get the 90 deg ones, they are the only ones that will fit.

 

[NMTerras]

I would just run what you already have in there. Did you pick up a pair of CEL eliminators already? If not, you will want to before you get started on this project.

Get the 90 deg ones, they are the only ones that will fit.

Yup, got a pair sitting in the garage.

 

[NMTerras]

Just waiting on short studs and gaskets and then it's go time

 

[drbandkgb]

I want some HEAD-ers

 

[Muadeeb]

Mods, can you do anything that user?

 

[Silver dude]

I'd run what you have till it leaks. The install of the headers doesn't effect the rest of the systems so much. The performance gain would be very minimal between the two setups. I always like doing mods one step at a time. Allows you to monitor the individual performance gain of every mod independently.

Ben

 

[02Xterra]

Here's what mine looks like Sean..

The OEM sizes are approximate.. but that's in line with what I've read from a couple forums..

 

[NMTerras]

How do you like it Shaun? How is the sound? That's very close to the setup I'm considering

 

[02Xterra]

I love it! It's got a very good rumble to it, especially just sitting at idle or in 4lo crawling thru the woods lol. Lil bit of rasp around 2500-3000 when its cold, but really not that bad. Above 3000 it sounds awesome haha. I'm very happy with it

 

[AZhiAZiAM]

this makes me want to buy headers...

 

[Timrich]

You and me both!

Sent from my Galaxy S III

 

[NMTerras]

Its in...sounds awesome...same thing with rasp at about 3k rpm when cold but otherwise fantastic


Sent from my brain using technology

 

[02Xterra]

Hell yea!

So did you end up replacing the entire exhaust?

 

[NMTerras]

Yep. Turned it over to an artist. New pipe, flomaster super 44 custom y from the headers w/ cels no cats


Sent from my brain using technology

 

[02Xterra]

Nice!!! I had to go with hi-flow cats to stay legal.. but the guy who did it has done exhausts for years a bunch of buddies of mine who have race cars.. dude is amazing at bending exhaust

 

[NMTerras]

Nice!!! I had to go with hi-flow cats to stay legal.. but the guy who did it has done exhausts for years a bunch of buddies of mine who have race cars.. dude is amazing at bending exhaust

I used a similar guy...long racing background. I can pass emissions here without the cats. I hope...and the dude's pipe work is awesome.

 

[02Xterra]

Looks great!! Looks just like mine lol

 

[AZhiAZiAM]

so question for you guys. i don't know much about headers. do the long tube headers replace cats? or just manifolds. i apparently cracked my manifold again or have a bad cat on my passenger side so im looking for options. either way i'd like to up grade those pos manifolds i currently have a flowmaster40 and was looking to hook it up kind like sean did.

 

[Muadeeb]

The Thorley's take up the space of the cats, but you'll need to figure out how to put them back on with the sensors in the right place to stay street legal.

 

[AZhiAZiAM]

so if i smog it i have to swap them out? i have a "smog guy"

 

[Muadeeb]

If you have "a guy" then do whatever "the guy" will let you get away with. Just be prepared if you have a roadside test station flag you.

 

[AZhiAZiAM]

damn lol. with my luck i will get pulled over too.. to take the risk or not to that is the question.

 

[Muadeeb]

Go Sean's route and completely redo the exhaust. That's what I'm doing if a cat actually goes on me, or if I ever pull the trigger on a set of Thorley's.

 

[AZhiAZiAM]

ya i'd do what sean has. i have the same muffler already and i have extra tubing sitting in the yard. and i got a local shop that does good work.

 

[SteeevO]

Just my 2 cents here. The setups that nmxterta and 02xterra have are highly recommended using the 2.5" pipe after the y.

Also I've got a few sets of headers here ready to ship.

Sent from my Desire HD using Tapatalk 2

 

[TKDx00]

Exhaust setup question...

Since the DT long tube headers eliminate the front cats, will a Catback exhaust still work? I'm guessing you clamp/weld/bolt the tubes to the header ends. However, does this make the overall reach shorter by the length of the cats to the back of the X or are custome bent tubes needed with the headers instead of the Catback system?

 

[Silver dude]

Since the headers are longer then the exhaust manifolds they mearly just take up the space the cats once were. They bolt up no mods to the factory exhaust system. Bolt flange to flange.

Ben

 

[SteeevO]

Exactly what Ben just said.

Sent from my Desire HD using Tapatalk 2

 

[TKDx00]

Since the headers are longer then the exhaust manifolds they mearly just take up the space the cats once were. They bolt up no mods to the factory exhaust system. Bolt flange to flange.

Ben

Thanks Ben, I've needed to change my exhaust for a while now but was waiting to do some other thing first. When I saw the diagram on the first page it started me wondering. Since IL. doesn't do a visual inspection, aren't we safe w/o cats or at worst I can use 2 Hi flow cats w/ a catback aftermarket setup?

 

[NMTerras]

All that "catback" means is the portion of the exhaust behind the catalytic converters...and the above is right, you can bolt your stock exhaust directly to the headers, but your cats will be gone. If you want to put in high-flow cats, you won't be able to use the stock exhaust, at least not direct bolt-on, because you'll need to find a place to put the cats behind the headers (like 02Xterra's setup). I chose to eliminate the cats, and put the CEL's in to fool the ECU. Make sure your emissions doesn't include a "sniffer" in the tailpipe if you choose to eliminate the cats from your exhaust

 

[drbandkgb]

All that "catback" means is the portion of the exhaust behind the catalytic converters...and the above is right, you can bolt your stock exhaust directly to the headers, but your cats will be gone. If you want to put in high-flow cats, you won't be able to use the stock exhaust, at least not direct bolt-on, because you'll need to find a place to put the cats behind the headers (like 02Xterra's setup). I chose to eliminate the cats, and put the CEL's in to fool the ECU. Make sure your emissions doesn't include a "sniffer" in the tailpipe if you choose to eliminate the cats from your exhaust

Our testing used to do the sniffer.. Now its all computer...

Even if you add the high flow cats your still going to have issues? I have been looking to fix my cracked mani but.. I need the Xterra to pass emissions..

 

[NMTerras]

With high flow cats you should be fine, but no warranty on that from me...

 

[TKDx00]

I need to make sure they don't put a probe in the tailpipe. I know they don't do a visual.