New Exhuast from header to Cat, need help for 2000 XJ

[robsjeepxj]

The stock exhaust is 2.5" all the way back to the rear cat after that it steps down to 2.25. I did a 2.5" in/out high flow cat and flowmaster muffler and 2.5" mandrel bent tailpipe and it is perfect I think. I left the pre cats as is and they are still going strong at almost 180,000 miles so if it aint broke... Also I'm pretty sure 3" will be way too large and will probably negatively effect your low end torque a lot and it will definitely be a cop magnet for sure as it will be obnoxiously loud.

 

[Fastdemise]

Look up Edelbrock Headers for the 00-01 Cali emissions XJ. It's what I'm looking at once my head cracks and since I have the head off might as well ya know.

 

[Gonepostal]

Hey bud how is the build going? You need to post up a pic or two. You are'nt missing much up here we have no roads open in the Big Horns and anywhere from four to eight feet of snow up there. Now its flooding here in town with a major rain storm and run off has yet to begin. Oh and if you haven't looked at Summit they did have some good deals with a rebate on cat backs and headers a while back. I'll check my e-mails and see if I can find the link with the rebate a friend sent me. If I have it I will post it up or PM ya.

 

[dieselenthusiast]

Look up Edelbrock Headers for the 00-01 Cali emissions XJ. It's what I'm looking at once my head cracks and since I have the head off might as well ya know.

Awesome, thanks for the info. Let me know if you buy one.

 

[dieselenthusiast]

Hey bud how is the build going? You need to post up a pic or two. You are'nt missing much up here we have no roads open in the Big Horns and anywhere from four to eight feet of snow up there. Now its flooding here in town with a major rain storm and run off has yet to begin. Oh and if you haven't looked at Summit they did have some good deals with a rebate on cat backs and headers a while back. I'll check my e-mails and see if I can find the link with the rebate a friend sent me. If I have it I will post it up or PM ya.

I’ll post up some pics soon. We are pretty high and dry here. We did get 5 inches of wet snow the other night. Sounds like you guys are swimming, lol. I'll send you a PM later on. Take it easy.......

 

[Gonepostal]

I'm going to attempt a trip up to check on my cabin on the Littlehorn River later this weekend, if the road isn't washed out. I may be posting some pics as well......Wonder if I can buy floats for the XJ?

 

[Fastdemise]

Awesome, thanks for the info. Let me know if you buy one.

Oh I want to real bad. Almost hoping I crack the 0331 head soon so I can a excuse to do it. haha

 

[dieselenthusiast]

Oh I want to real bad. Almost hoping I crack the 0331 head soon so I can a excuse to do it. haha

I know what you mean. I started a separate fund to put towards a new engine as my goal is to completely restore my XJ. I have 177,000 on my rig now and it seems to go on and on……. To take the burden off buying a new engine and all the accessories at one time, I am buying exhaust parts, cooling system parts, motor mounts, alternator, starter, etc. as I go. I already bought the dynomax catback, that’s why I’m currently looking for options for the header.

 

[wishihaddaxj]

So do the headers meant for 00-01s come with pre-cats? or incorporate the factory precats somehow?

Also: Could you conceivably switch from the Cali system to the Federal system if you switched computers (so it wouldn't throw a code)?

 

[Talyn]

The 00-01 precats are in the down pipe, not the header.

If you want to go to federal emissions you would need the PCM, wiring harness and correct O2 sensors and locations for them.

 

[dieselenthusiast]

So do the headers meant for 00-01s come with pre-cats? or incorporate the factory precats somehow?

Also: Could you conceivably switch from the Cali system to the Federal system if you switched computers (so it wouldn't throw a code)?

Some people would advise pulling the computers from a salvaged non-California emission XJ and swap them. That way you could go back with a non-California emissions exhaust. Instead of doing that, I don’t mind swapping to a new aftermarket California emissions header. I personally don’t think the California Emission package on these Jeeps are very restrictive, but I could be wrong.

 

[dieselenthusiast]

The 00-01 precats are in the down pipe, not the header.

They are? So it doesn't matter what header I go with? I just need a new OE downpipe or reuse the one that I have?

 

[robsjeepxj]

The headers for the pre cat setups are so short that they do virtually nothing, your wasting your money, the stock manifolds probably flow better since they are not making all the crazy turns the headers do. Look at them they're ridiculous.

 

[robsjeepxj]

Technically the pre cats are between the header and the down pipe at least on the stock set up, for serviceability, not sure about the aftermarket ones they maybe be all welded.

 

[Talyn]

You would need a header to fit the 00-01, not any.

Rodsjeepxj, its all those bends and twists that make the headers flow better than the factor cast iron crap.

 

[dieselenthusiast]

The headers for the pre cat setups are so short that they do virtually nothing, your wasting your money, the stock manifolds probably flow better since they are not making all the crazy turns the headers do. Look at them they're ridiculous.

I wish I could see some dyno results and underhood temp differences.

 

[robsjeepxj]

You would need a header to fit the 00-01, not any.

Rodsjeepxj, its all those bends and twists that make the headers flow better than the factor cast iron crap.

I can't see how that makes any sense? The manifolds are a straight shot, less resistance to flow.

 

[robsjeepxj]

I wish I could see some dyno results and underhood temp differences.

I'm sure the headers will increase the underhood temps which is already an issue on the 2000+ models. I can't see that helping the heat soak thing much. I just think for the size and design of the header for these it will just be a waste of time not too mention a huge PITA. Have you even changed an exhaust manifold on one of these? It suuuucks!!! Especially on a lifted jeep lift mine, it wasn't any fun at all.

 

[wishihaddaxj]

The headers for the pre cat setups are so short that they do virtually nothing, your wasting your money, the stock manifolds probably flow better since they are not making all the crazy turns the headers do. Look at them they're ridiculous.

See this is what I'm talkin about. Where I come from, the longer the primary tubes, the better. Those precats are way up there, so if the new "header" only goes from the engine to them, I'd be pretty disappointed. Therefore, if I were gonna add a header (for performance reasons, not to fix a crack), I'd get one for the federal standards and figure out what had to be done to make it work on my Cali-spec'd Jeep.

Edit: Hmm, I may have spoke too soon. For those interested: Link to JBA header install, keeping factory cats, complete with dyno.

 

[Talyn]

I can't see how that makes any sense? The manifolds are a straight shot, less resistance to flow.

No, that isn't how a header nor the exhaust system works. A proper header is designed with the RPM range of the engine and scavening effect. They are tuned for the engine.

Technically the pre cats are between the header and the down pipe at least on the stock set up, for serviceability, not sure about the aftermarket ones they maybe be all welded.

No, the precats are attached to the down pipe, there is nothing serviceable about them.