2001 xj. there is a leak at the flange where converter and muffler meet.
the bolts rusted through the cat converter side as shown in the picture.

So what to do? everything is original I believe. 140k ish miles.
The flanges on both side are solid and solidly connected to the pipe.
My plan was to remove the bolts and replace the hardware.
I cut the bolts and tried to drill out the holes on muffler flange. even with a cobalt bit i cant drill the ****!! its too heat treated barely made a dent.

So now what?
I could do a vat back replacement but im worried about other bolts for hanger placement breaking off. they look horrible and rusted to hell.

honeslty it seems like getting into this at all would mean cutting everything out with a torch that i dont have and replacing the whole system from manifolds back. All the connections are junk, not workable.

what do you guys think?

Hey guys, I need to replace my cat. I was trail riding and after 18 years of rust, its fell apart on the trail. Everything after the cat is fine, but I am taking the opportunity to replace the muffler as well due to rock damage. I believe the stock size exhaust tubing before the cat is 2.25". I am wondering if I should get a 2.5" cat and muffler so I can clamp the system down. Iv'e never had to replace this much of an exhaust system at once, and I think that I am overthinking things, but what are your opinions on this? Thanks in advance!

Hi, I have a 4cyl Cherokee that needed everything from the down pipe back. I bought everything and hooked it all up, and the new cat is too big for the factory downpipe. Is the downpipe from the 2.5 the same as a 4.0? The cat is obviously mounted in the same place on both but I have a feeling the downpipe is different. I have been unable to locate a downpipe specifically for the 2.5 and if the 4.0 is the same then I'll have my problem solved.

2.25" is the standard size piping of the 2.5L and 4.0L exhausts

Anyone running Borla XR-1 mufflers with stock setup? Looking for a replacement muffler with an aggressive note at idle and woot but minimal drone on cruising speeds.

After looking at stuff dealing with exhaust, not only on the I6 r I4 engines but exhaust science in general, it doesn't matter all too much so long as it stays consistent from the diameter change to the end of the exhaust. From what I can tell, most specialist recommend keeping the exhaust heads a bit closer to factory, as they initiate the exhaust velocity. Now with the Precat, cat, and muffler, there's a decent bit to restrict the exhaust on the jeeps, so most people move to a 2.5" from the pre-cats to the exhaust tip, I'm eventually looking to go this way myself. It will help flow, but it might be better to make the diameter transition closer to the precat than the cat. There's more to do with the muffler and how it is set up but I need to look more into that, but certain setups (glasspack vs. pipelines with holes) also affect the velocity even near the end of the line. So simple answer, go 2.5" if you want to help it breath a bit more. But you'll get a deeper tone and probably more drone because of it, if that bothers you.

I was just wondering if anyone knew what the original O2 sensors would have been on a 2000 XJ with a 4.0? I have just put a Golen 4.6 stroker into my xj and have been told by the engine builder that the engine doesn't really like to work with aftermarket O2 sensors/non-factory sensors. Thank you in advance!

NTK o2 sensors are the ones you want..

Thank you. Those are the ones that Bumper to Bumper told me were o.e. I just wanted to make sure though.

Try a couple of header washers

I have a 2000 Cherokee that I want to replace the exhaust on and am looking for the best budget set up.

I installed new walker pipes, with their quiet muffler and magnaflow high flow cat. Only a couple hundred bucks for the full exhaust.

Is it quiet like stock? I have the replacement muffler and a smaller Cat Conv on from like Midas etc, all those places say that is all that is available, unless get factory parts at a grand....mine is not bad but sounds like the muffler has hole in it...lol...is all new, but Midas, and other shops says being smaller is why louder and is all they can get...

Hey, I responded to your message. For anyone else who happens to be curious, the high flow cat gave me a little seat of the pants boost, while the walker quiet muffler kept it stock levels volume. I also replaced the downpipe and the final pipe piece with walker versions from amazon. With two new 02 sensors too I think I am in it $350 or $360, then I paid a muffler shop about $60 to weld it all up after I installed it. I would definitely recommend the setup for someone who is looking for an OEM+ type setup.

Anyone have MagnaFlow or Thunderbolt high flow cats? Did your MPG improve over stock? Power? Engine run cooler? Will they last long? (Not talking rust, I live in the south)