The whole exhaust fell off of my 91 XJ while on the interstate doing 70..... I put together a frankenstein exhaust system from cheap after market parts for about 120 bucks and it ran great and silent after that.

DUDE.... The XJ without a muffler is SO LOUD you will not be able to take it..... It sounds like a monster truck as its flooring it to jump and crush cars.... REALLY LOUD.

 

I went two weeks with an open cat after I mangled my muffler on the trail and it is super loud...not to mention I was only getting 120-140mi per 20gal tank on my basically stock xj. I now have a Dynomax cat back, sounds ok, wish it was a little louder/throatier...but it was super cheap and it works.