I'm running exactly the build you're planning, except my tires/wheels are stock. The MPG seems about normal, but it's really hard to tell in one of these things. If you're going to DD an XJ, you should make sure you're gonna be able to afford the gas no matter what. Even stock it gets pretty poor mileage, 14-16 city and 18-20 highway. And that's if you drive like a granny.

 

Alright thanks guys

 

So what I' thinking about doing is the following:
OME 3" lift with full leafs packs
Nates 4x4 bumpers
Roof rack
Moab wheels with 31" tires
Headers
Fuel injectors
Disk brake upgrade
Flowmaster super 40 muffler
Magnaflow high-flow cat
2.5" tail pipe
Complete sound system

Do you guys think I'm forgetting anything?

 

Steel rims weigh more than aluminum by quite a bit. Multiply that x4, and you've increased the overall weight of the vehicle.

With a 3" lift and 30" BFG A/T's on steel D-windows, I was getting 14-15mpg average, and over 20 just on the highway.

Since I installed my heavy @$$ 31" Guard Dogs, my MPG dropped to like 12-13 average.

My 3" lift alone didn't affect my MPG but the weight of the wheels and tires made a huge impact.

 

Ok then I'll make sure to avoid steel rims.

 

BUT.... they're good, because if you bash one on the trail, you can hammer it back out to get you home.

so you need to decide what is most important to you. Off-road or on-road.

 

I want this to be a DD so I'm probably gonna go with aluminums. I'm mostly going to be going to school and around town. Maybe a little light off roading here and there but eventually I want to get a trail only rig.

 

To add to my post above, I'm also considering a steering upgrade.