The K&N makes the biggest difference at high rpm (above 3000). I have never heard that the accel ignition system is worth it. A fan will help some but not much. Your best bet would be to go to www. turbocity.com (remove the space) and look under the Jeep power section. For the 500 you had mentioned you can get a lot more.

Nick Hagen
1995 Wrangler
33" Mud Tires and a four banger