The OP is after the sound...without breaking the bank, not the performance gains or lack thereof.

 

If that is all he is after, all he needs to do is go to YouTube and enter XJ exhaust, or Cherokee exhaust and listen. He doesn't need exhaust myths/bad info from someone on a forum.

 

The OP didn't ask for myths. He asked specific questions:

1. Has anyone ever put true dual exhaust on their xj's?
2. Is there room for pipes etc?
3. What do you do about o2 sensors?

 

Its been done google it.

 

Find a good custom exhaust guy and cut existing pipe just after o2s and run them out. Tricks gonna be two mufflers then up over rear axle split in front of tank and out the back. Staying 1 7/8 or 2 inch gonna be best size for small area along side of tank. Things are only as complicated as you make them.

 

U missed my point.....others (not the OP) r posting myths/misinformation.