3" Exhaust

[Green Mountain ZJ]

Here's the plan. I would like to build a 3" exhaust from the y-pipe back. I found Kevin's and this one from Summit http://store.summitracing.com/partde...5&autoview=sku for a cat-back. Specific questions that I would like to know:
1) Can I reuse the 02 sensors?
2) What is a good hi-flow cat to use? I like the one for Kevin's but all I can tell is that it is a Magnaflow. I would like to retain the downstream 02 sensor for Johnny Law purposes.
3) What is the best way to come off the y-pipe?
4) Are there any other complete kits out there?

Any help is appreciated.

[ILikeMud]

I don`t know of any 3 inch kits.
You can use your stock O2 sensor but make sure the cat has a bung for the sensor. Magnaflow aka Carsound cats are fairly good qaulity and cheap too.

[ZJRuss]

I think Kolak sells a kit, includes choice of muffler type and hi-flow cat. for your model year smog specs.

[jfowlzj95]

I think Kolak sells a kit, includes choice of muffler type and hi-flow cat. for your model year smog specs.

Also includes headers if you want them, good quality kits if you dont mind the $$$. kolak@aol.com

The one you see on Kevin's site is Kolak.

[Green Mountain ZJ]

OK, so

1) I can reuse my original o2 sensor, thanks Tony.

2) I found the cat w/ my 02 bung: http://store.summitracing.com/partde...0&autoview=sku

3) The best way to come off the y-pipe is apparently w/ a new y-pipe: http://store.summitracing.com/partde...0&autoview=sku

4) Still don't know of any other kits but I would rather make my own anyways w/ the Summit kit mentioned above.

I am not really interested in headers at the moment. Thanks all. Any other input or experiences is appreciated.

[Green Mountain ZJ]

Lately, I am getting the urge for a Clayton LA w/ a tax return in the near future. What do you need to do to a 3" exhaust to get it to fit? I thought I read about putting the cat and muffler closer to the y-pipe to make room for the LA crossmember and arms. What else should I be considering? What are other people running?

[ILikeMud]

To keep it simple, don't run a tail pipe.
Make sure to run a turn down on the muffler.

[Green Mountain ZJ]

To keep it simple, don't run a tail pipe.
Make sure to run a turn down on the muffler.

That would certainly simplify things. Is there a way to run it out the back or is it more work than it is worth? This thing still gets used as a family rig so I'm a little concerned about exhaust fumes.

[ILikeMud]

You shouldn't have a problem with exhaust fumes. I personally think the whole arguement is hersay.

You can run it out the back but it's best to have the long arm kit on just so you can route it around the 4 link with enough clearance.

[Green Mountain ZJ]

You shouldn't have a problem with exhaust fumes. I personally think the whole arguement is hersay.

You can run it out the back but it's best to have the long arm kit on just so you can route it around the 4 link with enough clearance.

Good point. The Summit kit comes w/ a pretty inexpensive Turbo muffler. I will put everything to together moving the cat and TM towards the front, then route it out the back. When the time comes for the LAs, I can separate the two sections and decide if the tailpipe can be guided through. It will also be a good time to decide whether the TM stays or goes. Thanks for the help.

[CurtP]

You shouldn't have a problem with exhaust fumes. I personally think the whole arguement is hersay.

I'll argue that point with you. I have a car that had an exhaust leak on the passenger side near the back seat. After driving for 10 minutes or so, anyone in the car would get light headed and end up with a splitting headache. I don't play around with that shit anymore - I route everything out the back and use an exhaust sealant on all the joints (Wurth exhaust system assembly paste). While many don't have a problem with exhaust gasses, I certainly did, and won't be making that mistake again. If you've been driving your vehicle and start to get a headache, it may not be from the drone. Not that I'm preaching, just another perspective.

On my 'Niner, I went with Nick's setup and had it Jet Hot coated. Just as a FYI, it's not a complete kit, per se. You will still need to fab up the connections between the downpipe and the cat and between the cat and the muffler (the kit is a tailpipe, muffler and cat). I don't recall it coming with muffler clamps either, but I don't remember for sure since I went with heavy-duty 1" wide stainless band clamps. I ended up having a local muffler shop do the install. They charged me $100 to fab up a stainless steel intermediate pipe and do the install. The guy told me he could have built me the entire thing out of 3" stainless (for less than what I paid), but I didn't know about this guy until I had already bought the system. Still, overall I'm happy with the setup (I went with the Magnaflow muffler). The cat Nick sells has the provision for the O2 sensor, along with a plug in case you don't need it (pre '96 OBDI).

I would recommend replacing the O2 sensors though - at least the upstream one.

[ILikeMud]

I'll argue that point with you. I have a car that had an exhaust leak on the passenger side near the back seat. After driving for 10 minutes or so, anyone in the car would get light headed and end up with a splitting headache. I don't play around with that shit anymore - I route everything out the back and use an exhaust sealant on all the joints (Wurth exhaust system assembly paste). While many don't have a problem with exhaust gasses, I certainly did, and won't be making that mistake again. If you've been driving your vehicle and start to get a headache, it may not be from the drone. Not that I'm preaching, just another perspective.

Never had this problem with my Jeep. Even with the windows up for hours on the highway. With and without my drain plugs in.
It could be different from vehicle to vehicle.

[CurtP]

Never had this problem with my Jeep. Even with the windows up for hours on the highway. With and without my drain plugs in.
It could be different from vehicle to vehicle.

Like I said, I wasn't preaching, just another perspective. It happened on my Formula back when I had the stock engine and tuning. The slip joint on the Borla intermediate pipe had slipped apart right where it starts to go up and over the axle. I never noticed it since it had a 3" wide band clamp covering the joint (BTW, Borla band clamps suck). The Borla on this particular application has a muffler bypass on it too, and at the time I had it wide open so I never could tell that there was an exhaust leak (it was stupid loud all the time). Since that time, I just don't take chances with it anymore, regardless of the application - everything gets routed out the back.

[ILikeMud]

I understand where your coming from Curt.

Oh and I think Borla sucks period.

[Green Mountain ZJ]

I'll argue that point with you. I have a car that had an exhaust leak on the passenger side near the back seat. After driving for 10 minutes or so, anyone in the car would get light headed and end up with a splitting headache. I don't play around with that shit anymore - I route everything out the back and use an exhaust sealant on all the joints (Wurth exhaust system assembly paste). While many don't have a problem with exhaust gasses, I certainly did, and won't be making that mistake again. If you've been driving your vehicle and start to get a headache, it may not be from the drone. Not that I'm preaching, just another perspective.

On my 'Niner, I went with Nick's setup and had it Jet Hot coated. Just as a FYI, it's not a complete kit, per se. You will still need to fab up the connections between the downpipe and the cat and between the cat and the muffler (the kit is a tailpipe, muffler and cat). I don't recall it coming with muffler clamps either, but I don't remember for sure since I went with heavy-duty 1" wide stainless band clamps. I ended up having a local muffler shop do the install. They charged me $100 to fab up a stainless steel intermediate pipe and do the install. The guy told me he could have built me the entire thing out of 3" stainless (for less than what I paid), but I didn't know about this guy until I had already bought the system. Still, overall I'm happy with the setup (I went with the Magnaflow muffler). The cat Nick sells has the provision for the O2 sensor, along with a plug in case you don't need it (pre '96 OBDI).

I would recommend replacing the O2 sensors though - at least the upstream one.

I appreciate the input. Has your performance changed much since you installed your exhaust? I've gotta believe it made a substantial improvement over the the stock pipe. 2.25" might work for a 4 banger but the V8 needs some breathing room. I like the fact that the 3" is an oversize single exhaust (vs. dual-not an option anyways). The best dual exhaust set-up has a crossover pipe which makes me think why bother. I'm no expert but I would be interested to see the performance differences between the two.

I've been contemplating changing out the o2 sensor (upstream) but have not heard any reason as to why it is a good idea other than your down there anyways. If the upstream sensor is bad, is it possible to swap it with the downstream sensor. The cat I mentioned above has the bung for an o2. I called up Magnaflow and they steered me in the right direction on that on. Thanks again for the input.

[CurtP]

I appreciate the input. Has your performance changed much since you installed your exhaust? I've gotta believe it made a substantial improvement over the the stock pipe. 2.25" might work for a 4 banger but the V8 needs some breathing room. I like the fact that the 3" is an oversize single exhaust (vs. dual-not an option anyways). The best dual exhaust set-up has a crossover pipe which makes me think why bother. I'm no expert but I would be interested to see the performance differences between the two.

I've been contemplating changing out the o2 sensor (upstream) but have not heard any reason as to why it is a good idea other than your down there anyways. If the upstream sensor is bad, is it possible to swap it with the downstream sensor. The cat I mentioned above has the bung for an o2. I called up Magnaflow and they steered me in the right direction on that on. Thanks again for the input.

I don't think the upstream and downstream sensors are interchangable - different part numbers and the connectors are different color as well. I didn't bother to check to see if the connections are the same though. O2 sensors get sluggish over time. If I'm going through the trouble of working on the exhaust system, I'll replace the O2's if they have anything over 50k on them. FWIW, I couldn't get the original downstream O2 out anyway.

I can't tell you what kind of performance increase there's going to be from just the exhaust. I did headers at the same time along with a K&N FIPK. I have since went back to the stock intake system that had a K&N drop-in and didn't notice any difference. I have recently replaced the K&N drop-in with a paper filter and still haven't noticed any difference. The only thing the FIPK gave me was a *lot* of intake noise and rubbing on the hood.

IMO, if you're going to do the exhaust, do headers too. Do it once, do it right and be done with it. Of course, if I had of known, I would have replaced my motor mounts while I was at it too. Live and learn...

[Green Mountain ZJ]

I don't think the upstream and downstream sensors are interchangable - different part numbers and the connectors are different color as well. I didn't bother to check to see if the connections are the same though. O2 sensors get sluggish over time. If I'm going through the trouble of working on the exhaust system, I'll replace the O2's if they have anything over 50k on them. FWIW, I couldn't get the original downstream O2 out anyway.

I can't tell you what kind of performance increase there's going to be from just the exhaust. I did headers at the same time along with a K&N FIPK. I have since went back to the stock intake system that had a K&N drop-in and didn't notice any difference. I have recently replaced the K&N drop-in with a paper filter and still haven't noticed any difference. The only thing the FIPK gave me was a *lot* of intake noise and rubbing on the hood.

IMO, if you're going to do the exhaust, do headers too. Do it once, do it right and be done with it. Of course, if I had of known, I would have replaced my motor mounts while I was at it too. Live and learn...

For any one else looking to do this there is another option. Instead of doing the Summit Cat back kit, you can get Dynomax to mandrel bend a 3" tailpipe. This allows you to choose your own muffler and is hella cheaper than the Summit kit. The Summit part # for the Dynomax tailpipe is WLK-44279. It is about $42. The Summit kit (about $145) includes the tailpipe, a $20 turbo muffler, clamps, and reducer that you won't need if you are coming off the y-pipe or header back. Kicking myself since I already ordered the Summit kit. The magnaflow cat is on backorder, so I have some time to gather the rest of the parts.

Big thanks to CurtP. Your post helped a lot. I am still looking for a good place to get a Mopar o2 sensor. Kevin sells them so I might just go that route. But other than that things are coming along nicely. The intake info was key as well.

[Popsicle]

Straight pipe the cat, or get a free flow cat, buy a muffler that you like, i personaly enjoy the flowmaster 30 or 40 series depending on taste, Down pipe it after. Im down piping my zj right now, and i have no problems AT ALL. So, ya. Barola does suck btw, too much $ for that kit

[CurtP]

3 of the 5 vehicles in this household have Borla cat-back systems on them. The ones on the '96 XJ and ZJ were actually cheap (less than $300/ea). Stainless steel, lifetime warranty - I'm happy.

The Borla on the XJ sounds like shit though...

[MikeyM]

Green Mountain (sounds like a place my wife wants to live) - for your O2 sensors, try www.jeepconnection.com. So far the lowest price on OEM parts I've found. I had to replace my sunroof relay - dealer wanted 201.00 Lawrence @ JC wanted 123.

OH.. it would be helpful if you could have both part numbers when calling them.

Mikey

[DCHZJ]

For the O2 Bungyou can just buy a weld-in bung and put it as close to the original spot as possible. I did this in my Bronco and it worked out fine. I also did this in my Grand as mine came with a cat back exhaust and i put a hiflow cat in. New O2 sensors, 1 piece of exhaust pipe with a weld in o2 bung and i passed emission testing in VA no problem.


I got my o2 sensor from Oxygen Sensor Wholesale
Ran them for a year without any problems.

[Green Mountain ZJ]

Thanks for the o2 sensor help. I'm still waiting for the 3" cat so results from said mod have yet to be discovered.

MikeyM - VT is AKA the green mountain state.

[dads5.9]

You definately want to wait until the Clayton's kit is on before doing any extensive exhaust work. Once the Clayton's is on NO stock exhaust is going to fit properly. You definately need a custom exhaust specifically bent to clear the long arms. We have 2 ZJs with Clayton's LA kits, it cost about $500 to have the local Meinheke shop build my son's with a new high flow cat and a magnaflo muffler and run the exhaust out the back.

I had them run mine straight back from the existing 3" cat with a 2.5" pipe out the back without a muffler, only $75. We do have headers on both, his is a 5.2 and mine is a 5.9. Mine had a 3" exhaust before we cut it off for the long arms and the new 2.5" straight pipe seems to have reduced my top end power, but I also went from 33" tires to 35" tires at the same time. I'm planning to go back and have a 3" exhaust constructed with a muffler to see if I get the top end performance back.

[JeeeeeeeeeeeeP]

look in my signature for a link to my Kolak 3" exhaust on a 5.2

New Y-pipe
Magnaflow hi flow cat
Magnaflow large oval muffler
kolak tailpipe

[Green Mountain ZJ]

look in my signature for a link to my Kolak 3" exhaust on a 5.2

New Y-pipe
Magnaflow hi flow cat
Magnaflow large oval muffler
kolak tailpipe

Yeah, that is the same one that KOR sells. I wanted to do something a little different than that.

The cat finally came in. We installed the exhaust 2 days ago. I am really happy w/ how it turned out so far. Even the Summit muffler has just the right sound. A little more rumble but not any too loud. The only snafu is the Check Engine light is on which could be one of two things. 1. We ran it w/ the cat and muffler but the downstream o2 sensor was not plugged in. Do I have to reset the computer or something? I was thinking about disconnecting the battery for awhile and hooking it back up to see if that would help. 2. I still need to order some new o2 sensors. Maybe that will cure it. It does seem to run good.