When your muffler is shot, what do you do...
 

My muffler and alot of the exhaust mount hardware is almost totally shot on my 2001 4.0L with about 150k miles.

Intake to tailpipe is totally stock except for a K&N air filter.

Do you think it's "worth it" to replace cat back or even headers to tailpipe when I repair this shyt?...or would you suggest to forget chasing any incremental HP and torque, and just replace the muffler and mount hardware with minimal cost. If the former, any good setups you recommend?

Appreciate your suggestions..

It depends on your budget. I wouldn't chase horsepower with XJ for me it would come down to the sound and quality of the replacement parts. I would complete an inspection of the complete exhaust system to begin and then replace what needs to be replaced.

I struggled with that question myself. '00. CA Emissions. I was getting a P0432. I also needed a new muffler and tailpipe. High flow cats maybe. Should I get a header since I am replacing the cat. Borla muffler and tailpipe maybe. With a decent header running about $350, $425 for the Borla, and Magnaflow high flow cats being through the roof said screw it. For a stock 4.0 with just a 4 hole injector upgrade figured it was not worth it. Just replaced the whole exhaust, front cat back, with Walker parts and called it a day. Now I toy with the idea about getting a motor built by a place local to me. Maybe not a stroker per se but a motor with a little something. Awhile back the opportunity to buy a TUPY head presented itself. $50. No idea of the condition. They would handle that for me too. If I were to go forward and do that then when it comes to exhaust I would bite the bullet and spend the money.

Do you have to pass an emissions test/inspection? The '01 has pre cats in the manifold, so, you may need to keep them. If not, a header, or even a manifold from a different year might be an improvement. The OEM "manifold" is already a header style, and if you don't have the pre-cats, I would never spend the money on an aftermarket header. WAY too expensive for too little gain. The factory design is not bad here.

With that said it might throw a code or something without the pre-cats, I'm not sure about those. I'm just glad I don't have any. :)

Aftermarket free flow cats are not very expensive. You can also get money for scrapping your OEM cat, it's full of precious metals. There are a lot of mufflers out there that sound way better than stock if you aren't going for silence...

it's a jeep, i like to keep them quiet. so i go stock replacement, walker parts.

for my harley... loud pipes save lives.

It's also the famous 4.0 inline 6, that comes with a very distinctive sound. It sounds very nice with the right muffler. It sounds like a broken UPS truck with the wrong exhaust. I like to let the sound out, but that's personal preference. (personally, I don't like unmuffled harleys)

As for "it's a jeep", Jeeps are supposed to make noise. It's not a Kia. Even the stock exhaust isn't exactly quiet...

IF you really want to hear a sad exhaust you should hear my 84 xj v6. The PO simply cut the exhaust off at the transmission mount. Said he was just using it around the ranch and didn't want to spend the money to replace the muffler.

Needless to say, when I get around to building it, I will be going back with the stock configuration. Nothing worse wheeling in the beauty of the mountains and listening to a AA fuel Dragster trying to cross a river....YUCK!

Don't get me wrong, loud has its place. I have a Harley and it's loud for a reason. That reason being I can let the cages on the road know I'm there. I don't abuse the loudness, but it's there if I need it.

Just my .02 worth.

Happy Jeepin'

If you want it not loud any oem replacement muffler well do,As far as any power gained from exhaust upgrades you might get 5hp which youll never really feel.

I was in the same situation as you. My Muffler was rotted and falling down. I looked online for the best deals. I listened to a lot of sound clips with different mufflers and tail pipes. The one that I liked the most was the Thrush Glass pack. I found one on craigslist for $15. The difference that I made is that I went with one that is for a larger vehicle. it is 2.5" diameter and 28 inches long. The one recommended for the Jeep is 2.25" diameter and 26 inches long. I have stock cat and tail pipe so 2.25" diameter. The larger diameter and longer length help give it a deeper sound then the standard glass pack. It gives a nice sound wile accelerating and is pretty quiet wile on the highway. It also has a nice tone wile at idle. I like the louder muffler in my jeep because I live out in the woods and there are a lot of critters that like to jump in the road.

I had an exhaust shop run 2.25 inch pipe from the headers back then I put a cheap $30 ebay muffler on it. It sounds good and cost me less than $120.
http://www.ebay.com/itm/Single-Chamb...dVbgdw&vxp=mtr

Stock replacement Walker from Advance Auto. I'm grown now, I don't wanna hear a loud exhaust anymore.

I agree, I almost went with a flowmaster setup from PerformanceCurve because the price was so low, but I managed to get a stock style replacement from a local shop, installed for $80.
It actually sounds pretty good, almost "stock+" if you will

Price was low, and I like my rig quiet for when I am wheeling in places I am not really supposed to :D

Maybe im getting old but im starting to like a not so loud exhaust now a days,Younger i always have glass packs on everything then spintech mufflers which are louder.Driving a loud car everyday can get anoyying and ring your ears,And worse case you could get electric exhaust cutouts if you want it loud and not at times.

i agree. even when i was younger, i had a 340 duster with headers and quiet mufflers until i opened it up.

loud mufflers are on underpowered cars/trucks and just annoying. good for kids.

my harley has stock pipes, for now, but v&h pipes and screamin eagle breather coming soon. but it's only a sporty, wanna keep it calm. next will be a glide with some grunt.

what do I do when half the exhaust is bad? Chop after the cat and put a short pipe with a turn down on it. cheap, CA legal, and sounds the same as a cherry bomb anyway. factory replacement exhaust manifold and downpipe from rockauto if necessary

Is that really legal? You pass a CA inspection that way? I thought exhaust was required to exit after any openings like passenger doors.

Mine is currently in that condition and I'm looking to replace the tailpipe and muffler, but, only so I can pass the NC inspection. If I don't need it, then I don't want it...

It depends your state if its legal or not,Honestly if its a daily driver i rather have it out the back,But if its a off road toy id run it short so it don't get banged up or ripped off.

it has to exit past the passenger compartment. since it's an SUV, it must exit past the rear most door (hatch).
if it was a pickup truck, it would be "legal", however, if the tech can't reach it during a emissions test, he won't test it, therefore you don't get your plate renewed. at least the last part is how it's done up here.

but a turn down in an SUV, you're looking to get sick and possibly kill yourself. or worse, a bus full of kittens.

Maybe in a rusted out POS. Carbon monoxide is odorless, but Jeep exhaust is not. You would know if the cab was leaking fumes, mine most certainly does not. I've driven various XJs for thousands of miles with the exhaust ending at the cat without so much as a turndown. If it passes any inspection in CA with a turndown, it can't be that bad.

My old Chevy pickup, on the other hand, with exhaust coming out at the rear bumper, reeks of exhaust inside. Funny how that works. No rust there either.

After doing more research, I think I am OK with just a turn down. I only need to pass a safety inspection - lights, wipers, brakes.

I am in the same boat atm. However I have the dreaded cracked exhaust header. I was given one that would allow for dual exhaust anyone ever ran dusls?

ok bud, it's your rig. i just hope you don't let any dogs or kids ride in your junk.

I've ran a turn down after the muffler for two years. Tired of that last section of pipe always rusting out. Whether in traffic, highway cruising, or cold weather warm ups, never had any issue with fumes in the cab. Even with Windows up or down. It really does matter of your rusted out underneath.

wow. drama queens unite!

bah. just caught me on a bad day. i'm over it.

Hahah, come on, we all have thick skin here and have our experiences and opinions. I also know caged is a good member here and respect his views.

debatable haha

I've passed multiple smog tests with the muffler chopped off. CA doesn't do inspections unless they are random smog check points, or if you're required to go visit a referee (usually to get a vehicle from non-op back to street registered). You're just not allowed to modify the exhaust before the cat if it changes the location of the cat.


as for the exhaust fumes, they are real. thinking about it now I would not recommend a turn down. I must've lost a few brain cells over the years :D but my jeep was doorless, it's harder to notice

Thanks to all the replies, many of which I've found helpful :D I was in London hence my delayed reply.

It's registered in Michigan so no emissions test. It's no longer a daily driver which is partly why I posted this thread.

From all I've read it's difficult and somewhat cost prohibitive to squeeze HP & torque out of the 4.0L, and frankly I can get by with the power from the 2001 powertrain.

Like the second poster said, I should inspect it all first to know what has to go and what doesn't. I'm certain all the hangers need to be replace, and the hardware because it's all rusted to shyt. Tubes and flanges are fine. Muffler is junk. Cat looks fine but probably doesn't "meow" anymore.

I'm favoring replacing Cat (go ahead, call me a tree hugger) to tail pipe, but leaving everything else, manifold to the input to the Cat. I've read about the dent in the down tube from the manifold, but haven't read an easy, affordable way to replace it, so I'll just leave it alone.

I have been searching this site looking for mods for horsepower as well. But most seem to be going loud. I have 2 kids under 6 and this will be a camping/skiing rig. Looking for as much horsepower but keeping cabin noise moderate. Off shelf cold air intakes for her seem to nonexistent and exhaust seem to focus on noise vs HP. Dont care about fuel economy, just looking to climb the altitude towing a camper or weekend of ski gear. Looking for advise with some miles on them, not brand new mods. Have a moderate budget so can't go nutty but not going cheap either. Thanks for everyone's advise and previous knowledge I have gained
Oh, I put 2" lift running 29's so HP should go farther.
but really sounds like the upgrade in muffler is all about sound and not HP for the cost. Maybe have them run 2.5" and see what they offer at the shop. Id like to open the intake as well, but not much on that I see. Ill look into this 4 hole injector and see where that gets me. thanks all
Bringing back to life an 89, 4.0 with 215k. 2 months in the garage with lots of oil leaks fixed, shes on her way to recovery.
cheers to another XJ back on the road