Alright so me and a friend of mine both have 2000 cherokee sports, the only difference is his has bigger tires and air shocks in the back, but his is way more powerful, it speeds up way faster and just sounds like a beast compared to mine, any reason it would be performing more powerful?

 

Running cleaner? Tune up kit maybe? Any performance mods maybe?

 

Give it a tune up,
Plugs
Cap/rotor
Wires
Seafoam
Clean IAC

 

No cap, rotor or wires in a 2000 XJ. Replace the plugs but don't expect too much unless you find the plugs really worn. Might seem faster because of the louder exhaust or the bigger tires.

 

Air Shocks on an XJ WOW that's not a good idea for sure and welcome to the board hope we may be able to answer your question.

The first thing that cones to mind is that tour friends XJ may have had a gear change when the larger tires were installed by him or in its past life. This is quite common on these XJ's as most were lifted at sometime in their life and larger tires with gears/lockers installed. The stock gear in the 4.0/AW4/NP231 4x4 were 3.55's.

General tune-ups with 4 hole injectors/Bored Throttle Bodies up-grades are common also among others to improve performance.

Soooooo......could be a lot of different things more information is really needed for a good answer.