I have a 97 jeep wrangler with a 2.5L and thru many trails and errors it has sevaral mods under the hood. Cold air intake sucks in larger amounts of air, catback with releases exaust out freely for complete easy breathing. NGK plugs for hotter spark, accel 8mm wires to carry that spark. My best modification is a throttle bodie spacer from gsppowerspacers.com. This spacer has proven itself to out perform other brands that fail to deliver highend torque and power. Thru experence when i tried others with the screw design they have no affect on higher RPMs or freeway speeds. What i like about this spacer you can feel the added throttle response, more torque and horse power and it also saves gas. Anyway what a throttle bodie spacer does is it sets under your throttle body it increases the air volume under there, to top this off it takes all the incoming air and causes it to inter the engine with more presure, volicity and force, thus resulting in better air/fuel mixture. The gsp power spacer is also different thanany other spacer i have ever seen. Let me tell you this lil puppy works great. hope i was of some help. feel free to write me anytime. Happy 4 wheeling. Quicksand97