I have a 97 with a 4 banger and use to want to get rid of it when I first got it. I use to have to lean foward on the highway just to do 55MPH. But after a few years lil by lil it all added up. Homemade cold air coming in from removed headlght bezels, with heat wrap on a bigger air tube, K&N filter, cut open factory air box to ram air in as a tunnel affect. 4.0L throttle body with flat top, custom throttle body spacer with velocity air blades, it has a 60mm bore on top and a 55mm bore on bottom. Intake manifold bored out from stock 48mm to 55mm. Accel 42,000 volt coil, accel 8mm wires, NGK plugs gapped at .039, maybe I will try bigger after I get some magnacor wires. magnaflow exhaust, catback. O yes I also trimmed my factory fan, just a tad and also bent some corners of blades at a 45 degree angle for less drag and she seems to wind up alot quicker. No problem with overheating. I only run 31in BFG muds. I also try to keep my jeep light. Angled front license plate for less drag. Hey every bit counts a these little beast. I also cut down front factory bumper for more clearance and less wieght. I gotta find a way to get rid of flat spots on bumper to reduce wind drag a bit more. Did you know that even wind hits the front diff and reduces MPG. Maybe a good angled skid plate will work. Anyway my lil monster is pretty quick and can climb up to 75 mph on highway no problem, she is also fast off the line with that spacer and 4.0L TB. She holds 65mph on a headwind uphill. I tell you one thing if I open up my factory air box any more I lose air charge thus reducing torque and top speed. In my expereance to much air in not good. Not enough not good. gotta find that sweet spot. Thats why I went with a homebrewed air box, I can adjust to my liking. How can one cold air intake fit all. Anyway I am super pleased with my lil rig for now. Just gotta stay with 31s until I can afford a different gears. Then I will go with bigger lift and tires. For now she just really fast. I gotta get some 2.5L stickers, I took old ones off when I first got her. Power to weight ratio, air, fuel, spark, FUN !