Could find some cams for the 2.4. Crane 16s are pretty mild with the long stroke of the 2.4. It'll make it more peaky though, which isn't exactly good for a crawler like a jeep. The 2.4 will respond well to a good intake manifold design, but again, losing runner length will make it slightly more lethargic between 1K and 3K rpms.
If you're feeling brave, the SRT-4 turbo bolts onto the head and can be found for around $200. A little work, an RRFPR, and some $$ later, you could have a jeep with a nice flat 200ft/lb torque curve from 1500 RPM up. Swap in SRT internals add more boost and fuel and bump that to 300 ft/lbs.
I'm rambling a little here. There are options for you, but not many of them are real good in the jeep's power band. A small turbo is the only thing that will put a big grin on your face.
As far as milage, Keep the air filter clean, don't haul around extra weight, and keep your foot out of it.
2011 Wrangler Rubicon, Zone 3" lift, 3/4" spacers, SRC Front and Rear bumpers, Bushwacker flares.